Abstract: An arrangement in connection with an adjustable back rest cushion (10,16), where the cushion is connected with a slide means (4,5) which may be moved in a guide (3) forming part of the back rest (1), said guide (3) consisting of a contoured rail spaced from the back rest front, said slide means (4,5) consisting of two members, viz. a slide member (5) which is designed to be movable in a groove in said rail, solely in the longitudinal direction of said rail, and a cushion holder member (4), which at its rear portion is pivotably attached (14) to one end of a front portion of slide member (5), and is lockable by the aid of a snap lock means (15, 15', 15") to the other end of said front portion of slide member (5), the front portion of cushion holder member (4) being provided with means (8) for engagement with cushion rear side (9).