A hospital bed includes a frame, a backrest unit, a driving unit, a leg support unit and a linkage unit. The frame includes posts supported on a floor. The backrest unit is pivotally connected to the frame. The leg support unit includes a portion pivotally connected to the frame and another portion pivotally connected to the backrest unit. The leg support unit is located opposite to the backrest unit on the frame. The driving unit includes a portion connected to the frame and another portion pivotally connected to the backrest unit. The linkage unit connects the leg support unit to the backrest unit.