Ventricular assist device (VAD) thrombosis is one of the most devastating complications for patients on mechanical assist devices, and has been occurring more frequently during the last 3 years for unknown reasons. The diagnosis of VAD thrombosis is challenging and requires knowledge of the various clinical presentations and high vigilance. The current review summarizes various aspects of VAD thrombosis, including possible mechanisms for the formation of VAD thrombus and its clinical presentation, and presents a suggested algorithm in diagnosing this entity, with therapeutic options. High awareness and knowledge of the variable clinical presentations of VAD thrombosis are essential in order to allow early diagnosis, which may decrease the morbidity and mortality associated with this complication.