Disclosed is a halogen incandescent lamp having a lamp vessel, which is sealed at one end and in which at least one luminous element is accommodated, a vessel section 42 being in the form of a side reflector which extends only over a subregion of the lamp vessel circumference. A light-exit window 40 adjoins this vessel section 42 in the circumferential direction. According to the invention, the light-exit window 40 is comparatively slightly curved in cross section, the vessel section 42 forming the side reflector bulging out away from the light-exit window 40. This bulged-out region is preferably provided with a kidney-shaped constriction 46.