We present a study of the effect of the spin–orbit interaction on the band structures in III-V binary semiconductor compounds like GaAs, GaP, GaSb, etc. Our calculations were performed using a self-consistent, full-potential linearized augmented plane wave (FP-LAPW) method as implemented in Wien2k code. We found that the inclusion of spin-orbit interaction affects on the band structures, and the splitting of degenerate valence band occurs on high symmetry G-point. We obtained the results on the band structures without and with the inclusion of spin-orbit interaction and compare the results. We also measured the value of the splitting energy and found that our results are similar to the calculated value of earlier results.