Optical gains in wurtzite–GaN strained quantum-well (QW) lasers are estimated theoretically for various crystallographic directions. The calculation of the valence subbands is based on thek⋅ptheory, where deformation potentials are determined by a semiempirical tight-binding method. It is found that the gains in GaN strained QW lasers with non-(0001) orientations, particularly around the (101¯5) orientation, are markedly high and anisotropic, unlike those in (0001)-oriented lasers. ©1997 American Institute of Physics.