diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index 05c235f5f51..d29fd0d5e15 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -1690,11 +1690,17 @@ class Form
 				$out .= '<select class="flat'.($moreclass ? ' '.$moreclass : '').'" id="'.$htmlid.'" name="'.$htmlname.(($num || empty($disableifempty)) ? '' : ' disabled').($multiple ? '[]' : '').'" '.($multiple ? 'multiple' : '').' '.(!empty($moreparam) ? $moreparam : '').'>';
 			}
 
-			if (($showempty == 1 || ($showempty == 3 && $num > 1)) && !$multiple) {
-				$out .= '<option value="0"'.(in_array(0, $selected) ? ' selected' : '').'>&nbsp;</option>';
+			if ($showempty && ! is_numeric($showempty)) {
+				$textforempty = $showempty;
+				$out .= '<option class="optiongrey" value="-1"'.(in_array(-1, $selected) ? ' selected' : '').'>'.$textforempty.'</option>';
 			}
-			if ($showempty == 2) {
-				$out .= '<option value="0"'.(in_array(0, $selected) ? ' selected' : '').'>-- '.$langs->trans("Internal").' --</option>';
+			else {
+				if (($showempty == 1 || ($showempty == 3 && $num > 1)) && ! $multiple) {
+					$out .= '<option value="0"'.(in_array(0, $selected) ? ' selected' : '').'>&nbsp;</option>';
+				}
+				if ($showempty == 2) {
+					$out .= '<option value="0"'.(in_array(0, $selected) ? ' selected' : '').'>-- '.$langs->trans("Internal").' --</option>';
+				}
 			}
 
 			$i = 0;
diff --git a/htdocs/langs/en_US/projects.lang b/htdocs/langs/en_US/projects.lang
index e73a21dea26..77eabd20221 100644
--- a/htdocs/langs/en_US/projects.lang
+++ b/htdocs/langs/en_US/projects.lang
@@ -197,6 +197,7 @@ InputPerMonth=Input per month
 InputDetail=Input detail
 TimeAlreadyRecorded=This is time spent already recorded for this task/day and user %s
 ProjectsWithThisUserAsContact=Projects with this user as contact
+ProjectsWithThisContact=Projects with this contact
 TasksWithThisUserAsContact=Tasks assigned to this user
 ResourceNotAssignedToProject=Not assigned to project
 ResourceNotAssignedToTheTask=Not assigned to the task
diff --git a/htdocs/langs/fr_FR/projects.lang b/htdocs/langs/fr_FR/projects.lang
index 950462968ed..ee3736acef0 100644
--- a/htdocs/langs/fr_FR/projects.lang
+++ b/htdocs/langs/fr_FR/projects.lang
@@ -197,6 +197,7 @@ InputPerMonth=Saisie par mois
 InputDetail=Saisir le détail
 TimeAlreadyRecorded=C'est le temps passé déjà enregistré pour cette tâche/jour et pour l'utilisateur %s
 ProjectsWithThisUserAsContact=Projets avec cet utilisateur comme contact
+ProjectsWithThisContact=Projets avec ce contact
 TasksWithThisUserAsContact=Tâches assignées à cet utilisateur
 ResourceNotAssignedToProject=Non assigné au projet
 ResourceNotAssignedToTheTask=Non assigné à la tache
diff --git a/htdocs/projet/list.php b/htdocs/projet/list.php
index 6019011956a..b19bc407537 100644
--- a/htdocs/projet/list.php
+++ b/htdocs/projet/list.php
@@ -98,6 +98,7 @@ $search_opp_amount = GETPOST("search_opp_amount", 'alpha');
 $search_budget_amount = GETPOST("search_budget_amount", 'alpha');
 $search_public = GETPOST("search_public", 'int');
 $search_project_user = GETPOST('search_project_user', 'int');
+$search_project_contact = GETPOST('search_project_contact', 'int');
 $search_sale = GETPOST('search_sale', 'int');
 $search_usage_opportunity = GETPOST('search_usage_opportunity', 'int');
 $search_usage_task = GETPOST('search_usage_task', 'int');
@@ -253,6 +254,7 @@ if (empty($reshook)) {
 		$search_public = "";
 		$search_sale = "";
 		$search_project_user = '';
+		$search_project_contact = '';
 		$search_sday = "";
 		$search_smonth = "";
 		$search_syear = "";
@@ -364,13 +366,14 @@ if (empty($user->rights->projet->all->lire)) {
 
 // Get id of types of contacts for projects (This list never contains a lot of elements)
 $listofprojectcontacttype = array();
-$sql = "SELECT ctc.rowid, ctc.code FROM ".MAIN_DB_PREFIX."c_type_contact as ctc";
+$listofprojectcontacttypeexternal = array();
+$sql = "SELECT ctc.rowid, ctc.code, ctc.source FROM ".MAIN_DB_PREFIX."c_type_contact as ctc";
 $sql .= " WHERE ctc.element = '".$db->escape($object->element)."'";
-$sql .= " AND ctc.source = 'internal'";
 $resql = $db->query($sql);
 if ($resql) {
 	while ($obj = $db->fetch_object($resql)) {
-		$listofprojectcontacttype[$obj->rowid] = $obj->code;
+		if ($obj->source == 'internal') $listofprojectcontacttype[$obj->rowid] = $obj->code;
+		else $listofprojectcontacttypeexternal[$obj->rowid] = $obj->code;
 	}
 } else {
 	dol_print_error($db);
@@ -378,6 +381,9 @@ if ($resql) {
 if (count($listofprojectcontacttype) == 0) {
 	$listofprojectcontacttype[0] = '0'; // To avoid sql syntax error if not found
 }
+if (count($listofprojectcontacttypeexternal) == 0) {
+	$listofprojectcontacttypeexternal[0] = '0'; // To avoid sql syntax error if not found
+}
 
 $distinct = 'DISTINCT'; // We add distinct until we are added a protection to be sure a contact of a project and task is only once.
 $sql = "SELECT ".$distinct." p.rowid as id, p.ref, p.title, p.fk_statut as status, p.fk_opp_status, p.public, p.fk_user_creat,";
@@ -418,6 +424,9 @@ if ($search_sale > 0) {
 if ($search_project_user > 0) {
 	$sql .= ", ".MAIN_DB_PREFIX."element_contact as ecp";
 }
+if ($search_project_contact > 0) {
+	$sql .= ", ".MAIN_DB_PREFIX."element_contact as ecp_contact";
+}
 $sql .= " WHERE p.entity IN (".getEntity('project').')';
 if (!empty($conf->categorie->enabled)) {
 	$sql .= Categorie::getFilterSelectQuery(Categorie::TYPE_PROJECT, "p.rowid", $search_category_array);
@@ -502,6 +511,9 @@ if ($search_sale > 0) {
 if ($search_project_user > 0) {
 	$sql .= " AND ecp.fk_c_type_contact IN (".$db->sanitize(join(',', array_keys($listofprojectcontacttype))).") AND ecp.element_id = p.rowid AND ecp.fk_socpeople = ".((int) $search_project_user);
 }
+if ($search_project_contact > 0) {
+	$sql .= " AND ecp_contact.fk_c_type_contact IN (".$db->sanitize(join(',', array_keys($listofprojectcontacttypeexternal))).") AND ecp_contact.element_id = p.rowid AND ecp_contact.fk_socpeople = ".((int) $search_project_contact);
+}
 if ($search_opp_amount != '') {
 	$sql .= natural_search('p.opp_amount', $search_opp_amount, 1);
 }
@@ -690,6 +702,9 @@ if ($search_public != '') {
 if ($search_project_user != '') {
 	$param .= '&search_project_user='.urlencode($search_project_user);
 }
+if ($search_project_contact != '') {
+	$param .= '&search_project_user='.urlencode($search_project_contact);
+}
 if ($search_sale > 0) {
 	$param .= '&search_sale='.urlencode($search_sale);
 }
@@ -809,6 +824,11 @@ if (empty($user->rights->user->user->lire)) {
 $moreforfilter .= img_picto($tmptitle, 'user', 'class="pictofixedwidth"').$form->select_dolusers($search_project_user ? $search_project_user : '', 'search_project_user', $tmptitle, '', 0, $includeonly, '', 0, 0, 0, '', 0, '', 'maxwidth250');
 $moreforfilter .= '</div>';
 
+$moreforfilter .= '<div class="divsearchfield">';
+$tmptitle = $langs->trans('ProjectsWithThisContact');
+$moreforfilter .= img_picto($tmptitle, 'user', 'class="pictofixedwidth"').$form->selectcontacts(0, $search_project_contact ? $search_project_contact : '', 'search_project_contact', $tmptitle);
+$moreforfilter .= '</div>';
+
 // If the user can view thirdparties other than his'
 if ($user->rights->societe->client->voir || $socid) {
 	$langs->load("commercial");