A backrest (1) for a wheelchair, comprising: - an adjustable cushion support (10), for supporting a backrest cushion, said cushion support (10) defining substantially a plane P1； - a backrest frame (20), for holding said cushion support (10), said backrest frame having two substantially parallel side posts (21a, 21b) defining substantially a plane P2； - attachment members (3), for attaching said cushion support (10) to said backrest frame (20)； - said cushion support (10) comprising two side bars (11a, 11b) and a plurality of transversally extending and vertically spaced apart flexible straps (14) each interconnecting said two side bars (11a, 11b), each strap having length- adjusting means for adjusting the length of said straps； - said cushion support (10) comprising at least two connecting plates (12a, 12b), each plate (12a, 12b) being integral with one of said side bars (11a, 11b) and being provided with at least two parallel adjustment slots (13, 13', 13"), said slots defining an angle a, .alpha.>；0, with said plane P1； - said attachment members (3) being slidably mounted on said slots (13, 13', 13"), enabling depth, width and angular adjustment of said cushion support (10) on said backrest frame (20).
