Abstract: A wheelchair has a base with a pair of wheels connected to each side of the base, a seat pivotally connected to the base, a backrest pivotally connected to the seat and a transmitting mechanism for pivoting the seat and the backrest. The transmitting mechanism includes a seat bracket secured to the seat, a seat shaft received in the seat bracket, a front gear and a rear respectively mounted on two end of the seat shaft, a main shaft slidably received in the base and extending into the seat bracket, a back shaft securely connected with the backrest and extending into the seat bracket, a back gear mounted on the back shaft and engaging with the rear gear, a seat gear and a main gear mounted on the main shaft and engaging with the front gear alternately. By such an arrangement, the seat and the backrest can be pivoted to an upright position or horizontal position to assist a disabled person to stand up or lie on the wheelchair.