However, first team outings have been fleeting in recent times, Molenaar last starting against Worcester back in February.
An opportunity has now presented itself for Molenaar to link up with Harlequins, and he will go straight into their A League side on Monday evening.
Director of Rugby Nigel Davies explained that the chance to play more rugby was the main reason behind Molenaar's departure.
"Tim has been a popular member of the squad in his time here and, even though he has not had many chances in the first team recently, has been a good professional.
"With Harlequins having some injuries in their squad, there is a chance for Tim to get some more playing time at the Stoop, so we have agreed to release him.
"We would like to think him for all his efforts over the past four seasons and wish him all the best for the future."
