The band structure of indirect-band gap semiconductors ͑AlAs, GaP͒ as well as indirect-band gap alloys semiconductors ͑GeSi͒ is described theoretically by using a 30ϫ 30 k ϫ p model including the d far-level contribution. For all materials investigated, the resulting electronic band structure parameters are in good agreement with experimental values. The method also provides a good description of the second conduction band which is useful for transport modeling. Finally, our results show that Luttinger parameters, the valence band parameter, and the effective masses in the X and L valleys are in good agreement with available experimental data.