diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index 2929b66e80c..7570b89d9f9 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -4191,10 +4191,11 @@ abstract class CommonObject
 		return true;
 	}
 	
-	 /**
-	 * define buy price if not defined
+	/**
+	 * Get buy price to use for margin calculation. This function is called when buy price is unknown.
 	 *	set buy price = sell price if ForceBuyingPriceIfNull configured,
-	 *	 else if calculation MARGIN_TYPE = 'pmp' and pmp is calculated, set pmp as buyprice
+	 *   else if calculation MARGIN_TYPE = 'costprice' and costprice is defined, use costprice as buyprice
+	 *	 else if calculation MARGIN_TYPE = 'pmp' and pmp is calculated, use pmp as buyprice
 	 *	 else set min buy price as buy price
 	 *	 
 	 * @param float		$unitPrice		 product unit price
@@ -4209,16 +4210,16 @@ abstract class CommonObject
 	
 		$buyPrice = 0;
 		
-		if (($unitPrice > 0) && (isset($conf->global->ForceBuyingPriceIfNull) && $conf->global->ForceBuyingPriceIfNull == 1))
+		if (($unitPrice > 0) && (isset($conf->global->ForceBuyingPriceIfNull) && $conf->global->ForceBuyingPriceIfNull == 1)) // In most cases, test here is false
 		{
 			$buyPrice = $unitPrice * (1 - $discountPercent / 100);
 		}
 		else
 		{
-			// Get PMP
+			// Get cost price for margin calculation
 			if (! empty($fk_product))
 			{
-				if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == 'pmp')
+				if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == 'costprice')
 				{
 					require_once DOL_DOCUMENT_ROOT.'/product/class/product.class.php';
 					$product = new Product($this->db);
@@ -4228,13 +4229,32 @@ abstract class CommonObject
 						$this->errors[] = 'ErrorProductIdDoesNotExists';
 						return -1;
 					}
-					if (($product->pmp > 0))
+					if ($product->cost_price > 0)
+					{
+						$buyPrice = $product->cost_price;
+					}
+					else if ($product->pmp > 0)
 					{
 						$buyPrice = $product->pmp;
 					}
-					// TODO add option to set PMP of product
 				}
-				else if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == '1')
+				else if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == 'pmp')
+				{
+					require_once DOL_DOCUMENT_ROOT.'/product/class/product.class.php';
+					$product = new Product($this->db);
+					$result = $product->fetch($fk_product);
+					if ($result <= 0)
+					{
+						$this->errors[] = 'ErrorProductIdDoesNotExists';
+						return -1;
+					}
+					if ($product->pmp > 0)
+					{
+						$buyPrice = $product->pmp;
+					}
+				}
+				
+				if (empty($buyPrice) && isset($conf->global->MARGIN_TYPE) && in_array($conf->global->MARGIN_TYPE, array('1','pmp','costprice')))
 				{
 					require_once DOL_DOCUMENT_ROOT.'/fourn/class/fournisseur.product.class.php';
 					$productFournisseur = new ProductFournisseur($this->db);
diff --git a/htdocs/core/tpl/objectline_create.tpl.php b/htdocs/core/tpl/objectline_create.tpl.php
index 31ad9716155..e17648a7643 100644
--- a/htdocs/core/tpl/objectline_create.tpl.php
+++ b/htdocs/core/tpl/objectline_create.tpl.php
@@ -521,30 +521,56 @@ jQuery(document).ready(function() {
     	  		var defaultkey = '';
     	  		var defaultprice = '';
 	      		var bestpricefound = 0;
+	      		
+	      		var bestpriceid = 0; var bestpricevalue = 0;
+	      		var pmppriceid = 0; var pmppricevalue = 0;
+	      		var costpriceid = 0; var costpricevalue = 0;
+
+				/* setup of margin calculation */
+	      		var defaultbuyprice = '<?php 
+	      		if (isset($conf->global->MARGIN_TYPE))
+	      		{
+	      		    if ($conf->global->MARGIN_TYPE == '1')   print 'bestsupplierprice';
+	      		    if ($conf->global->MARGIN_TYPE == 'pmp') print 'pmp';
+	      		    if ($conf->global->MARGIN_TYPE == 'costprice') print 'costprice';
+	      		} ?>';
+	      		console.log("defaultbuyprice="+defaultbuyprice);
+	      		
 	      		var i = 0;
 	      		$(data).each(function() {
-	      			if (this.id != 'pmpprice')
+	      			if (this.id != 'pmpprice' && this.id != 'costprice')
 		      		{
 		        		i++;
-                        this.price = parseFloat(this.price);//fix this.price >0
-
+                        this.price = parseFloat(this.price); // to fix when this.price >0
 			      		// If margin is calculated on best supplier price, we set it by defaut (but only if value is not 0)
-		      			var defaultbuyprice = '<?php echo ((isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == '1')?'bestsupplierprice':''); ?>';	// We set here default value to use
-			      		console.log(this.id+" "+this.price+" "+defaultbuyprice+" "+(this.price > 0));
-		      			if (bestpricefound == 0 && this.price > 0 && 'bestsupplierprice' == defaultbuyprice) { defaultkey = this.id; defaultprice = this.price; bestpricefound=1; }	// bestpricefound is used to take the first price > 0
+			      		console.log("id="+this.id+"-price="+this.price+"-"+(this.price > 0));
+		      			if (bestpricefound == 0 && this.price > 0) { defaultkey = this.id; defaultprice = this.price; bestpriceid = this.id; bestpricevalue = this.price; bestpricefound=1; }	// bestpricefound is used to take the first price > 0
 		      		}
 	      			if (this.id == 'pmpprice')
 	      			{
 	      				// If margin is calculated on PMP, we set it by defaut (but only if value is not 0)
-		      			var defaultbuyprice = '<?php echo ((isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == 'pmp')?'pmp':''); ?>';
-			      		console.log(this.id+" "+this.price+" "+defaultbuyprice);
-		      			if (this.price > 0 && 'pmp' == defaultbuyprice) { defaultkey = this.id; defaultprice = this.price; }
+			      		console.log("id="+this.id+"-price="+this.price);
+			      		if ('pmp' == defaultbuyprice || 'costprice' == defaultbuyprice)
+			      		{
+			      			if (this.price > 0) { defaultkey = this.id; defaultprice = this.price; pmppriceid = this.id; pmppricevalue = this.price;
+			      			console.log("pmppricevalue="+pmppricevalue); }
+			      		}
+	      			}
+	      			if (this.id == 'costprice')
+	      			{
+	      				// If margin is calculated on Cost price, we set it by defaut (but only if value is not 0)
+			      		console.log("id="+this.id+"-price="+this.price+"-pmppricevalue="+pmppricevalue);
+			      		if ('costprice' == defaultbuyprice)
+			      		{
+		      				if (this.price > 0) { defaultkey = this.id; defaultprice = this.price; costpriceid = this.id; costpricevalue = this.price; }
+		      				else if (pmppricevalue > 0) { defaultkey = pmppriceid; defaultprice = pmppricevalue; }
+			      		}
 	      			}
 	        		options += '<option value="'+this.id+'" price="'+this.price+'">'+this.label+'</option>';
 	      		});
 	      		options += '<option value="inputprice" price="'+defaultprice+'"><?php echo $langs->trans("InputPrice"); ?></option>';
 
-	      		console.log("defaultkey="+defaultkey);
+	      		console.log("finally selected defaultkey="+defaultkey+" defaultprice="+defaultprice);
 
 	      		$("#fournprice_predef").html(options).show();
 	      		if (defaultkey != '')
diff --git a/htdocs/fourn/ajax/getSupplierPrices.php b/htdocs/fourn/ajax/getSupplierPrices.php
index 9a94553930d..794a0addcf4 100644
--- a/htdocs/fourn/ajax/getSupplierPrices.php
+++ b/htdocs/fourn/ajax/getSupplierPrices.php
@@ -1,6 +1,7 @@
 <?php
 /* Copyright (C) 2012      Christophe Battarel  <christophe.battarel@altairis.fr>
- * Copyright (C) 2015      Francis Appels      <francis.appels@z-application.com>
+ * Copyright (C) 2015      Francis Appels       <francis.appels@z-application.com>
+ * Copyright (C) 2016      Laurent Destailleur  <eldy@users.sourceforge.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -18,7 +19,7 @@
 
 /**
  *	\file       /htdocs/fourn/ajax/getSupplierPrices.php
- *	\brief      File to return an Ajax response to get a supplier prices
+ *	\brief      File to return an Ajax response to get list of possible prices for margin calculation
  */
 
 if (! defined('NOTOKENRENEWAL')) define('NOTOKENRENEWAL','1'); // Disables token renewal
@@ -36,6 +37,8 @@ $idprod=GETPOST('idprod','int');
 $prices = array();
 
 $langs->load('stocks');
+$langs->load('margins');
+
 
 /*
  * View
@@ -92,6 +95,10 @@ if ($idprod > 0)
 	// Add price for pmp
 	$price=$producttmp->pmp;
 	$prices[] = array("id" => 'pmpprice', "price" => price2num($price), "label" => $langs->trans("PMPValueShort").': '.price($price,0,$langs,0,0,-1,$conf->currency), "title" => $langs->trans("PMPValueShort").': '.price($price,0,$langs,0,0,-1,$conf->currency));  // For price field, we must use price2num(), for label or title, price()
+
+	// Add price for costprice
+	$price=$producttmp->cost_price;
+	$prices[] = array("id" => 'costprice', "price" => price2num($price), "label" => $langs->trans("CostPrice").': '.price($price,0,$langs,0,0,-1,$conf->currency), "title" => $langs->trans("PMPValueShort").': '.price($price,0,$langs,0,0,-1,$conf->currency));  // For price field, we must use price2num(), for label or title, price()
 }
 
 echo json_encode($prices);
diff --git a/htdocs/langs/en_US/margins.lang b/htdocs/langs/en_US/margins.lang
index 4cfaa989cd1..b705f25ba42 100644
--- a/htdocs/langs/en_US/margins.lang
+++ b/htdocs/langs/en_US/margins.lang
@@ -35,8 +35,9 @@ MargeBrute=Raw margin
 MargeNette=Net margin
 MargeType1=Margin on Best supplier price
 MargeType2=Margin on Weighted Average Price (WAP)
-MARGIN_TYPE_DETAILS=Raw margin : Selling price - Buying price<br/>Net margin : Selling price - Cost price
-MarginTypeDesc=Margin on best buying price : Selling price - Best supplier price defined on product card<br/>Margin on Weighted Average Price (WAP) : Selling price - Product Weighted Average Price (WAP) or best supplier price if WAP not yet defined
+MargeType3=Margin on Cost Price
+MARGIN_TYPE_DETAILS=Raw margin : Selling price - Buying price<br>Net margin : Selling price - Cost price
+MarginTypeDesc=* Margin on best buying price = Selling price - Best supplier price defined on product card<br>* Margin on Weighted Average Price (WAP) = Selling price - Product Weighted Average Price (WAP) or best supplier price if WAP not yet defined<br>* Margin on Cost price = Selling price - Cost price defined on product card or WAP if cost price not defined, or best supplier price if WAP not yet defined
 CostPrice=Cost price
 BuyingCost=Cost price
 UnitCharges=Unit charges
diff --git a/htdocs/margin/admin/margin.php b/htdocs/margin/admin/margin.php
index 706d14ebe12..6e84b13e286 100644
--- a/htdocs/margin/admin/margin.php
+++ b/htdocs/margin/admin/margin.php
@@ -1,5 +1,6 @@
 <?php
 /* Copyright (C) 2012	Christophe Battarel	<christophe.battarel@altairis.fr>
+ * Copyright (C) 2016	Laurent Destailleur	<eldy@users.sourceforge.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -145,20 +146,15 @@ if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == '1')
 print '/> ';
 print $langs->trans('MargeType1');
 print '<br>';
-/*print $langs->trans('MargeNette');
-print ' <input type="radio" name="MARGIN_TYPE" value="2" ';
-if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == '2')
-	print 'checked ';
-print '/>';*/
-// TODO Check that PMP is available when stock module is not enabled. If not, make this choice greyed when stock module disabled.
-//if (! empty($conf->stock->enabled))
-//{
-	print ' <input type="radio" name="MARGIN_TYPE" value="pmp" ';
-	if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == 'pmp')
-		print 'checked ';
-	print '/> ';
-	print $langs->trans('MargeType2');
-//}
+print ' <input type="radio" name="MARGIN_TYPE" value="pmp" ';
+if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == 'pmp') print 'checked ';
+print '/> ';
+print $langs->trans('MargeType2');
+print '<br>';
+print ' <input type="radio" name="MARGIN_TYPE" value="costprice" ';
+if (isset($conf->global->MARGIN_TYPE) && $conf->global->MARGIN_TYPE == 'costprice') print 'checked ';
+print '/> ';
+print $langs->trans('MargeType3');
 print '</td>';
 print '<td>';
 print '<input type="submit" class="button" value="'.$langs->trans("Modify").'" class="button">';
diff --git a/htdocs/product/class/product.class.php b/htdocs/product/class/product.class.php
index 8c744fbb6d3..a0703d73caf 100644
--- a/htdocs/product/class/product.class.php
+++ b/htdocs/product/class/product.class.php
@@ -106,6 +106,8 @@ class Product extends CommonObject
 
 	//! Stock
 	var $stock_reel;
+	//! Cost price
+	var $cost_price;
 	//! Average price value for product entry into stock (PMP)
 	var $pmp;
     //! Stock alert