A wheelchair rehabilitation device (1.2) mountable on a framework (1.1.1) of a wheelchair (1.1) having a pair of rear wheels connected with a shaft characterized In that the wheelchair rehabilitation device (1.2) is removably mountable on the front end and on a side of a framework (1.1.1) of wheelchair (1.1); the wheelchair rehabilitation device (1.2) comprises a frame (1.2.1) and a pedal propulsion system comprising: - pedals rotatable by a crankshaft, and transmission sprockets (8.1, 8.2), a crankshaft drive sprocket (9.2), a second propulsion transmission means (10.2), a guide; and - a rear drive sprocket (9.1), a first propulsion transmission means (10.1), a tensioning mechanism; the pedal propulsion system is interconnectable with the propulsion of wheelchair's rear wheels; the wheelchair rehabilitation device's (1.2) frame (1.2.1) is removably mountable on the front-end of a wheelchair's (1.1) framework (1.1.1) by means of quick couplings; the transmission sprockets (8.1, 8.2), the crankshaft drive sprocket (9.2), the rear drive sprocket (9.1), the propulsion transmission means (10.1, 10.2) with the guide and the tensioning mechanism are mountable on a same side of the wheelchair rehabilitation device's (1.2) frame (1.2.1) and the wheelchair's (1.1) framework (1.1.1); wherein - the rear drive sprocket (9.1) is mountable on the shaft of wheelchair's rear wheel; - the first propulsion transmission means (10.1) is mountable on the rear drive sprocket (9.1) and on the first transmission sprocket (8.1); - the second propulsion transmission means (10.2) is mountable on the crankshaft drive sprocket (9.2) and on the second transmission sprocket (8.2); the transmission sprockets (8.1, 8.2) are interconnected and mountable next to each other; - the propulsion transmission means (10.1,10.2) are at an angle to each other; - the pedals are in horizontally extended position in relation to the wheelchair (1.1); wherein the pedal propulsion system is configured so that power from the first and second propulsion transmission means (10.1, 10.2) is transmitted through the first and second transmission sprockets (8.1, 8.2) so that translational motion of the wheelchair's rear wheels causes rotational motion of the crankshaft, and vice versa. the wheelchair rehabilitation device (1.2) is removably mountable on the front end and on a side of a framework (1.1.1) of wheelchair (1.1); the wheelchair rehabilitation device (1.2) comprises a frame (1.2.1) and a pedal propulsion system comprising: - pedals rotatable by a crankshaft, and transmission sprockets (8.1, 8.2), a crankshaft drive sprocket (9.2), a second propulsion transmission means (10.2), a guide; and - a rear drive sprocket (9.1), a first propulsion transmission means (10.1), a tensioning mechanism; - pedals rotatable by a crankshaft, and transmission sprockets (8.1, 8.2), a crankshaft drive sprocket (9.2), a second propulsion transmission means (10.2), a guide; and - a rear drive sprocket (9.1), a first propulsion transmission means (10.1), a tensioning mechanism; the pedal propulsion system is interconnectable with the propulsion of wheelchair's rear wheels; the wheelchair rehabilitation device's (1.2) frame (1.2.1) is removably mountable on the front-end of a wheelchair's (1.1) framework (1.1.1) by means of quick couplings; the transmission sprockets (8.1, 8.2), the crankshaft drive sprocket (9.2), the rear drive sprocket (9.1), the propulsion transmission means (10.1, 10.2) with the guide and the tensioning mechanism are mountable on a same side of the wheelchair rehabilitation device's (1.2) frame (1.2.1) and the wheelchair's (1.1) framework (1.1.1); wherein - the rear drive sprocket (9.1) is mountable on the shaft of wheelchair's rear wheel; - the first propulsion transmission means (10.1) is mountable on the rear drive sprocket (9.1) and on the first transmission sprocket (8.1); - the second propulsion transmission means (10.2) is mountable on the crankshaft drive sprocket (9.2) and on the second transmission sprocket (8.2); the transmission sprockets (8.1, 8.2) are interconnected and mountable next to each other; - the propulsion transmission means (10.1,10.2) are at an angle to each other; - the pedals are in horizontally extended position in relation to the wheelchair (1.1); - the rear drive sprocket (9.1) is mountable on the shaft of wheelchair's rear wheel; - the first propulsion transmission means (10.1) is mountable on the rear drive sprocket (9.1) and on the first transmission sprocket (8.1); - the second propulsion transmission means (10.2) is mountable on the crankshaft drive sprocket (9.2) and on the second transmission sprocket (8.2); the transmission sprockets (8.1, 8.2) are interconnected and mountable next to each other; - the propulsion transmission means (10.1,10.2) are at an angle to each other; - the pedals are in horizontally extended position in relation to the wheelchair (1.1); wherein the pedal propulsion system is configured so that power from the first and second propulsion transmission means (10.1, 10.2) is transmitted through the first and second transmission sprockets (8.1, 8.2) so that translational motion of the wheelchair's rear wheels causes rotational motion of the crankshaft, and vice versa.