diff --git a/calendar/inc/class.calendar_boupdate.inc.php b/calendar/inc/class.calendar_boupdate.inc.php
index e8c54b17f9..fe6d15b53a 100644
--- a/calendar/inc/class.calendar_boupdate.inc.php
+++ b/calendar/inc/class.calendar_boupdate.inc.php
@@ -1067,6 +1067,18 @@ class calendar_boupdate extends calendar_bo
 			{
 				// recalculate alarms to also cope with moved events (beside server time adjustment)
 				$event['alarm'][$id]['time'] = $event['start'] - $alarm['offset'];
+
+				// remove alarms belonging to not longer existing or rejected participants
+				if ($alarm['owner'] && isset($event['participants']))
+				{
+					$status = $event['participants'][$alarm['owner']];
+					if (!isset($status) || calendar_so::split_status($status) === 'R')
+					{
+						unset($event['alarm'][$id]);
+						$this->so->delete_alarm($id);
+						error_log(__LINE__.': '.__METHOD__."(".array2string($event).") deleting alarm=".array2string($alarm).", $status=".array2string($alarm));
+					}
+				}
 			}
 		}
 		// update all existing alarm times, in case alarm got moved and alarms are not include in $event
@@ -1077,7 +1089,19 @@ class calendar_boupdate extends calendar_bo
 				if (!isset($event['alarm'][$id]))
 				{
 					$alarm['time'] = $event['start'] - $alarm['offset'];
-					$this->so->save_alarm($event['id'],$alarm, $this->now);
+					// remove (not store) alarms belonging to not longer existing or rejected participants
+					$status = isset($event['participants']) ? $event['participants'][$alarm['owner']] :
+						$old_event['participants'][$alarm['owner']];
+					if (!$alarm['owner'] || isset($status) && calendar_so::split_status($status) !== 'R')
+					{
+						$this->so->save_alarm($event['id'], $alarm, $this->now);
+						error_log(__LINE__.': '.__METHOD__."() so->save_alarm($event[id], ".array2string($alarm).", $this->now)");
+					}
+					else
+					{
+						$this->so->delete_alarm($id);
+						error_log(__LINE__.': '.__METHOD__."(".array2string($event).") deleting alarm=".array2string($alarm).", $status=".array2string($alarm));
+					}
 				}
 			}
 		}
@@ -1303,6 +1327,17 @@ class calendar_boupdate extends calendar_bo
 				is_numeric($uid)?$uid:substr($uid,1),$status,
 				$recur_date?$this->date2ts($recur_date,true):0,$role)))
 		{
+			if ($status == 'R')	// remove alarms belonging to rejected participants
+			{
+				foreach(isset($event['alarm']) ? $event['alarm'] : $old_event['alarm'] as $id => $alarm)
+				{
+					if ((string)$alarm['owner'] === (string)$uid)
+					{
+						$this->so->delete_alarm($id);
+						error_log(__LINE__.': '.__METHOD__."(".array2string($event).", '$uid', '$status', ...) deleting alarm=".array2string($alarm).", $status=".array2string($alarm));
+					}
+				}
+			}
 			if ($updateTS)
 			{
 				$GLOBALS['egw']->contenthistory->updateTimeStamp('calendar', $cal_id, 'modify', $this->now);
diff --git a/calendar/inc/class.calendar_so.inc.php b/calendar/inc/class.calendar_so.inc.php
index 1ac46c0971..a5fa63e558 100644
--- a/calendar/inc/class.calendar_so.inc.php
+++ b/calendar/inc/class.calendar_so.inc.php
@@ -1020,7 +1020,7 @@ ORDER BY cal_user_type, cal_usre_id
 
 		$old_min = $old_duration = 0;
 
-		//error_log(__METHOD__.'('.array2string($event).",$set_recurrences,$change_since,$etag)");
+		//error_log(__METHOD__.'('.array2string($event).",$set_recurrences,$change_since,$etag) ".function_backtrace());
 
 		$cal_id = (int) $event['id'];
 		unset($event['id']);
@@ -1435,10 +1435,11 @@ ORDER BY cal_user_type, cal_usre_id
 	 * splits the combined status, quantity and role
 	 *
 	 * @param string &$status I: combined value, O: status letter: U, T, A, R
-	 * @param int &$quantity only O: quantity
-	 * @param string &$role only O: role
+	 * @param int &$quantity=null only O: quantity
+	 * @param string &$role=null only O: role
+	 * @return string status U, T, A or R, same as $status parameter on return
 	 */
-	static function split_status(&$status,&$quantity,&$role)
+	static function split_status(&$status,&$quantity=null,&$role=null)
 	{
 		$quantity = 1;
 		$role = 'REQ-PARTICIPANT';
@@ -1453,6 +1454,7 @@ ORDER BY cal_user_type, cal_usre_id
 		{
 			$status = 'U';
 		}
+		return $status;
 	}
 
 	/**
@@ -1888,8 +1890,7 @@ ORDER BY cal_user_type, cal_usre_id
 	 */
 	function save_alarm($cal_id, $alarm, $update_modified=true)
 	{
-		//echo "<p>save_alarm(cal_id=$cal_id, alarm="; print_r($alarm); echo ")</p>\n";
-		//error_log(__METHOD__."(.$cal_id,$now,".array2string($alarm).')');
+		//error_log(__METHOD__."($cal_id, ".array2string($alarm).', '.array2string($update_modified).') '.function_backtrace());
 		if (!($id = $alarm['id']))
 		{
 			$alarms = $this->read_alarms($cal_id);	// find a free alarm#
@@ -1932,6 +1933,7 @@ ORDER BY cal_user_type, cal_usre_id
 	 */
 	private function delete_alarms($cal_id)
 	{
+		//error_log(__METHOD__."($cal_id) ".function_backtrace());
 		$alarms = $this->read_alarms($cal_id);
 
 		foreach($alarms as $id => $alarm)
@@ -1952,6 +1954,7 @@ ORDER BY cal_user_type, cal_usre_id
 	 */
 	function delete_alarm($id)
 	{
+		//error_log(__METHOD__."('$id') ".function_backtrace());
 		// update the modification information of the related event
 		list(,$cal_id) = explode(':',$id);
 		if ($cal_id)
diff --git a/calendar/inc/class.calendar_uiforms.inc.php b/calendar/inc/class.calendar_uiforms.inc.php
index ae3ef43793..5b13c69ca8 100644
--- a/calendar/inc/class.calendar_uiforms.inc.php
+++ b/calendar/inc/class.calendar_uiforms.inc.php
@@ -405,6 +405,17 @@ class calendar_uiforms extends calendar_ui
 										{
 											$msg = lang('Status changed');
 										}
+										if ($status == 'R' && $event['alarm'])
+										{
+											// remove from bo->set_status deleted alarms of rejected users from UI too
+											foreach($event['alarm'] as $alarm_id => $alarm)
+											{
+												if ((string)$alarm['owner'] === (string)$uid)
+												{
+													unset($event['alarm'][$alarm_id]);
+												}
+											}
+										}
 									}
 									if (!$preserv['no_popup'])
 									{