diff --git a/htdocs/projet/card.php b/htdocs/projet/card.php
index 7852e985c04f8..c4f5559fa7632 100644
--- a/htdocs/projet/card.php
+++ b/htdocs/projet/card.php
@@ -68,6 +68,7 @@
 $date_start_event = dol_mktime(GETPOST('date_start_eventhour', 'int'), GETPOST('date_start_eventmin', 'int'), GETPOST('date_start_eventsec', 'int'), GETPOST('date_start_eventmonth', 'int'), GETPOST('date_start_eventday', 'int'), GETPOST('date_start_eventyear', 'int'));
 $date_end_event = dol_mktime(GETPOST('date_end_eventhour', 'int'), GETPOST('date_end_eventmin', 'int'), GETPOST('date_end_eventsec', 'int'), GETPOST('date_end_eventmonth', 'int'), GETPOST('date_end_eventday', 'int'), GETPOST('date_end_eventyear', 'int'));
 $location = GETPOST('location', 'alphanohtml');
+$fk_project = GETPOST('fk_project', 'int');
 
 
 $mine = GETPOST('mode') == 'mine' ? 1 : 0;
@@ -205,6 +206,7 @@
 			$db->begin();
 
 			$object->ref             = GETPOST('ref', 'alphanohtml');
+			$object->fk_project      = GETPOST('fk_project', 'int');
 			$object->title           = GETPOST('title', 'alphanohtml');
 			$object->socid           = GETPOST('socid', 'int');
 			$object->description     = GETPOST('description', 'restricthtml'); // Do not use 'alpha' here, we want field as it is
@@ -304,6 +306,7 @@
 			$old_start_date = $object->date_start;
 
 			$object->ref          = GETPOST('ref', 'alpha');
+			$object->fk_project   = GETPOST('fk_project', 'int');
 			$object->title        = GETPOST('title', 'alphanohtml'); // Do not use 'alpha' here, we want field as it is
 			$object->statut       = GETPOST('status', 'int');
 			$object->socid        = GETPOST('socid', 'int');
@@ -603,6 +606,14 @@
 	// Label
 	print '<tr><td><span class="fieldrequired">'.$langs->trans("Label").'</span></td><td><input class="width500 maxwidth150onsmartphone" type="text" name="title" value="'.dol_escape_htmltag(GETPOST("title", 'alphanohtml')).'" autofocus></td></tr>';
 
+	// Parent
+	if (getDolGlobalInt('PROJECT_ENABLE_SUB_PROJECT')) {
+		print '<tr><td>'.$langs->trans("Parent").'</td><td class="maxwidthonsmartphone">';
+		print img_picto('', 'project', 'class="pictofixedwidth"');
+		$formproject->select_projects(-1, '', 'fk_project', 64, 0, 1, 1, 0, 0, 0, '', 0, 0, '', '', '');
+		print '</td></tr>';
+	}
+
 	// Usage (opp, task, bill time, ...)
 	if (!empty($conf->global->PROJECT_USE_OPPORTUNITIES) || empty($conf->global->PROJECT_HIDE_TASKS) || isModEnabled('eventorganization')) {
 		print '<tr><td class="tdtop">';
@@ -970,6 +981,14 @@ function change_percent()
 		print ajax_combobox('status');
 		print '</td></tr>';
 
+		// Parent
+		if (getDolGlobalInt('PROJECT_ENABLE_SUB_PROJECT')) {
+			print '<tr><td>'.$langs->trans("Parent").'</td><td class="maxwidthonsmartphone">';
+			print img_picto('', 'project', 'class="pictofixedwidth"');
+			$formproject->select_projects(-1, $object->fk_project, 'fk_project', 64, 0, 1, 1, 0, 0, 0, '', 0, 0, '', '', '');
+			print '</td></tr>';
+		}
+
 		// Usage
 		if (!empty($conf->global->PROJECT_USE_OPPORTUNITIES) || empty($conf->global->PROJECT_HIDE_TASKS) || isModEnabled('eventorganization')) {
 			print '<tr><td class="tdtop">';
@@ -1246,6 +1265,14 @@ function set_usage_event() {
 		if (!empty($object->thirdparty->id) && $object->thirdparty->id > 0) {
 			$morehtmlref .= $object->thirdparty->getNomUrl(1, 'project');
 		}
+		// Parent
+		if (getDolGlobalInt('PROJECT_ENABLE_SUB_PROJECT')) {
+			if (!empty($object->fk_project) && $object->fk_project) {
+				$parent = new Project($db);
+				$parent->fetch($object->fk_project);
+				$morehtmlref .= $langs->trans("Child of").' '.$parent->getNomUrl(1, 'project').' '.$parent->title;
+			}
+		}
 		$morehtmlref .= '</div>';
 
 		// Define a complementary filter for search of next/prev ref.
@@ -1618,6 +1645,41 @@ function change_percent()
 		print '<div class="fichecenter"><div class="fichehalfleft">';
 		print '<a name="builddoc"></a>'; // ancre
 
+		if (getDolGlobalInt('PROJECT_ENABLE_SUB_PROJECT')) {
+			/*
+			 * Sub-projects (children)
+			 */
+			$children = $object->getChildren();
+			if ($children) {
+				print '<table class="centpercent notopnoleftnoright table-fiche-title">';
+				print '<tr class="titre"><td class="nobordernopadding valignmiddle col-title">';
+				print '<div class="titre inline-block">'.$langs->trans('Sub-projects').'</div>';
+				print '</td></tr></table>';
+
+				print '<div class="div-table-responsive-no-min">';
+				print '<table class="centpercent noborder'.($morecss ? ' '.$morecss : '').'">';
+				print '<tr class="liste_titre">';
+				print getTitleFieldOfList('Ref', 0, $_SERVER["PHP_SELF"], '', '', '', '', '', '', '', 1);
+				print getTitleFieldOfList('Title', 0, $_SERVER["PHP_SELF"], '', '', '', '', '', '', '', 1);
+				print getTitleFieldOfList('Status', 0, $_SERVER["PHP_SELF"], '', '', '', '', '', '', '', 1);
+				print '</tr>';
+				print "\n";
+
+				$subproject = new Project($db);
+				foreach ($children as $child) {
+					$subproject->fetch($child->rowid);
+					print '<tr class="oddeven">';
+					print '<td class="nowraponall">'.$subproject->getNomUrl(1, 'project').'</td>';
+					print '<td class="nowraponall tdoverflowmax125">'.$child->title.'</td>';
+					print '<td class="nowraponall">'.$subproject->getLibStatut(5).'</td>';
+					print '</tr>';
+				}
+
+				print '</table>';
+				print '</div>';
+			}
+		}
+
 		/*
 		 * Generated documents
 		 */
diff --git a/htdocs/projet/class/project.class.php b/htdocs/projet/class/project.class.php
index 076dae11a0090..ac13af7d25a9a 100644
--- a/htdocs/projet/class/project.class.php
+++ b/htdocs/projet/class/project.class.php
@@ -82,6 +82,11 @@ class Project extends CommonObject
 	 */
 	protected $table_ref_field = 'ref';
 
+	/**
+	 * @var int parent project
+	 */
+	public $fk_project;
+
 	/**
 	 * @var string description
 	 */
@@ -291,6 +296,7 @@ class Project extends CommonObject
 	 */
 	public $fields = array(
 		'rowid' =>array('type'=>'integer', 'label'=>'ID', 'enabled'=>1, 'visible'=>-1, 'notnull'=>1, 'position'=>10),
+		'fk_project' =>array('type'=>'integer', 'label'=>'Parent', 'enabled'=>1, 'visible'=>1, 'notnull'=>0, 'position'=>12),
 		'ref' =>array('type'=>'varchar(50)', 'label'=>'Ref', 'enabled'=>1, 'visible'=>1, 'showoncombobox'=>1, 'position'=>15, 'searchall'=>1),
 		'title' =>array('type'=>'varchar(255)', 'label'=>'ProjectLabel', 'enabled'=>1, 'visible'=>1, 'notnull'=>1, 'position'=>17, 'showoncombobox'=>2, 'searchall'=>1),
 		'entity' =>array('type'=>'integer', 'label'=>'Entity', 'default'=>1, 'enabled'=>1, 'visible'=>3, 'notnull'=>1, 'position'=>19),
@@ -426,6 +432,7 @@ public function create($user, $notrigger = 0)
 
 		$sql = "INSERT INTO ".MAIN_DB_PREFIX."projet (";
 		$sql .= "ref";
+		$sql .= ", fk_project";
 		$sql .= ", title";
 		$sql .= ", description";
 		$sql .= ", fk_soc";
@@ -458,6 +465,7 @@ public function create($user, $notrigger = 0)
 		$sql .= ", ip";
 		$sql .= ") VALUES (";
 		$sql .= "'".$this->db->escape($this->ref)."'";
+		$sql .= ", ".($this->fk_project ? ((int) $this->fk_project) : "null");
 		$sql .= ", '".$this->db->escape($this->title)."'";
 		$sql .= ", '".$this->db->escape($this->description)."'";
 		$sql .= ", ".($this->socid > 0 ? $this->socid : "null");
@@ -570,6 +578,7 @@ public function update($user, $notrigger = 0)
 
 			$sql = "UPDATE ".MAIN_DB_PREFIX."projet SET";
 			$sql .= " ref='".$this->db->escape($this->ref)."'";
+			$sql .= ", fk_project=".($this->fk_project ? ((int) $this->fk_project) : "null");
 			$sql .= ", title = '".$this->db->escape($this->title)."'";
 			$sql .= ", description = '".$this->db->escape($this->description)."'";
 			$sql .= ", fk_soc = ".($this->socid > 0 ? $this->socid : "null");
@@ -680,7 +689,7 @@ public function fetch($id, $ref = '', $ref_ext = '', $email_msgid = '')
 			return -1;
 		}
 
-		$sql = "SELECT rowid, entity, ref, title, description, public, datec, opp_amount, budget_amount,";
+		$sql = "SELECT rowid, entity, fk_project, ref, title, description, public, datec, opp_amount, budget_amount,";
 		$sql .= " tms, dateo as date_start, datee as date_end, date_close, fk_soc, fk_user_creat, fk_user_modif, fk_user_close, fk_statut as status, fk_opp_status, opp_percent,";
 		$sql .= " note_private, note_public, model_pdf, usage_opportunity, usage_task, usage_bill_time, usage_organize_event, email_msgid,";
 		$sql .= " accept_conference_suggestions, accept_booth_suggestions, price_registration, price_booth, max_attendees, date_start_event, date_end_event, location, extraparams";
@@ -709,6 +718,7 @@ public function fetch($id, $ref = '', $ref_ext = '', $email_msgid = '')
 				$this->id = $obj->rowid;
 				$this->entity = $obj->entity;
 				$this->ref = $obj->ref;
+				$this->fk_project = $obj->fk_project;
 				$this->title = $obj->title;
 				$this->description = $obj->description;
 				$this->date_c = $this->db->jdate($obj->datec);
@@ -2480,4 +2490,31 @@ public function getKanbanView($option = '', $arraydata = null)
 		$return .= '</div>';
 		return $return;
 	}
+
+	/**
+	 *  Return array of sub-projects of the current project
+	 *
+	 *  @return		array		Children of this project as objects with rowid & title as members
+	 */
+	public function getChildren()
+	{
+		$children = [];
+		$sql = 'SELECT rowid,title';
+		$sql .= ' FROM '.MAIN_DB_PREFIX.'projet';
+		$sql .= ' WHERE fk_project = '.((int) $this->id);
+		$sql .= ' ORDER BY title';
+		$result = $this->db->query($sql);
+		if ($result) {
+			$n = $this->db->num_rows($result);
+			while ($n) {
+				$children[] = $this->db->fetch_object($result);
+				$n--;
+			}
+			$this->db->free($result);
+		} else {
+			dol_print_error($this->db);
+		}
+
+		return $children;
+	}
 }