The present invention relates to a wheelchair (10) comprising a wheelchair frame (1) resting on wheels (2, 3) and supporting a seat (4), and a backrest frame (5) supporting a backrest (6), said backrest frame (5) being pivotally connected to said wheelchair frame (1) and comprising two lateral tubular elements (5a), wherein each tubular element (5a) comprises an upper end portion (5b) provided with a handle (5d) and a lower end portion (5c) pivotally mounted on an axis (7) supported on a support (11) fixedly connected to the wheelchair frame (1), characterized in that locking/unlocking means (12) are provided for preventing the lower end portion (5c) of at least one of said tubular elements (5a), and preferably of each one of said tubular elements, to pivot relative to the corresponding support (11) in a locked inclined position of the backrest frame (5), said locking/unlocking means (12) being configured so as to permit a stepless adjustment of the angle (α0) between a plane (P1) defined by the backrest (6) and a plane (P2) defined by the seat (4) in said locked inclined position.
