Abstract: A chair with backrest that can be inclined backwards has a seat carried by a support (2b), connected by means of an articulated-parallelogram system (11, 12) to the fixed supporting structure (4, 10) of the chair. The support (17) of the backrest is articulated to the support (2b) of the seat and is operatively connected to said articulated-parallelogram system so that any reclining backwards of the backrest causes a raising and a slight inclination backwards of the seat. The support of the backrest (17) is moreover connected by means of an articulated arm (23) to a sliding support (2a), on which the seat is mounted (2), and is in turn mounted so that it can slide in a longitudinal direction (A) on seat support (2b).

Abstract: The backrest of a chair is adjustable continuously so that it can be positioned at any height between a fully lowered position and a fully raised position. The backrest includes a supporting member which is slidably mounted on a supporting upright and provided with a one-way locking mechanism which holds the backrest locked at any selected height.