Abstract: A motor-vehicle door includes a door body composed of a door frame member and inner and outer door panels attached to opposite sides of the door frame member, and a window sash assembly connected to an upper part of the door frame member. The window sash assembly includes a sash body, a window panel vertically movably held in the sash body, and a window regulator mounted on a lower portion of the sash body for moving the window panel up and down and holding it in position. Since the window panel and the window regulator are assembled in the window sash assembly as an integral part of the window sash assembly, the motor-vehicle door having such window sash assembly is simple in construction and can be assembled easily, precisely and less costly. Methods of assembling the motor-vehicle door are also disclosed.