We report on the anisotropic polarization of the luminescence observed in ZnSe-based heterostructure lasers. It has been found that light originating from the radiative recombination of electrons and holes confined in the ZnCdSe quantum well of the laser is linearly polarized collinearly to one ⟨110⟩ crystallographic direction after having passed thep-type region of the laser diode. A strong dependence of the laser operation on the two possible ⟨110⟩ directions of cleaved facets is observed. ©1998 American Institute of Physics.