A door frame for motor vehicles includes a window channel laterally defined by an outer door panel and an inner door panel, wherein the outer door panel and the inner door panel are provided adjacent of the window opening with longitudinally extending stiffening or reinforcement members located in the window channel. The reinforcement members are circumferentially closed tubular sections having an essentially oval cross-section, wherein the reinforcement members are adapted in their shape to the inner surfaces of the outer door panel and the inner door panel.