Conventional dental treatment chairs have a complicated mechanical adjustment mechanism which simultaneously ensures that the backrest is displaced relative to the body of the patient on pivoting the chair from an upright seating position into a horizontal lying position, which creates an unpleasant feeling. In the dental treatment chair (1) the seat element (4) and the backrest (5) are integrally formed as an essentially rigid shell with the seat frame (3). The seat frame (3) is convexly curved on its lower side (6) and mounted so as to be displaceable about an imaginary pivot axis (11) located at a distance above the seat frame (3) on a support frame (10) whose height is adjustable relative to the basic frame (2). The treatment chair is employed in dental treatments. <IMAGE>
