A dental impression tray which in a modular system can be assembled from a plurality of portions which can be connected together and is thus individually adaptable to the patient jaw situation. There may be a universal base tray with insertable additional parts both for lower jaw and also for upper jaw impressions, wherein further adaptation can be implemented by extension portions and by shortening of the portions on the basis of predetermined markings or desired breaking locations. The impression tray may be a thermoplastic material which can be heated and still more precisely formed to the respective jaw geometry within the patient's mouth.