A backrest for a wheelchair includes an adjustable cushion support, a backrest frame, and attachment members. The adjustable cushion support supports a backrest cushion, and substantially defines plane P1. The backrest frame holds the cushion support and has two substantially parallel side posts substantially defining a plane P2. The attachment members attach the cushion support to the backrest frame. The cushion support comprises two side bars and a plurality of transversally extending and vertically spaced apart flexible straps. Each strap is length adjustable. The cushion support comprises at least two connecting plates. Each plate being integral with one of the side bars and being provided with at least two parallel adjustment slots. The slots define an angle α, with said plane P1 of the adjustable support cushion. The attachment members are slidably mounted on the slots, enabling depth, width and angular adjustment of the cushion support on the backrest frame.
