Sneijder has been nothing short of a revelation since breaking into the Ajax team last term, while Heitinga has battled back from serious injury to cement a regular place in Ronald Koeman's plans.
Koeman, fresh from signing his own deal, felt the duo deserved recognition for their efforts, with the club rewarding them with deals which run until the summer of 2007.
Sneijder was a virtual unknown last season, but took the rise to prominence in his stride and the midfielder is now a regular for both club and country.
He only signed a new deal in May, which tied him to the club until 2007, but his efforts this term have been rewarded with improved terms.
Heitinga made the breakthrough way back in the summer of 2001, but was struck down by injuries last term.
He battled back to fitness over the course of the summer and is being tipped for a Holland call up in the near future.
