We reportabinitiostudies on the electronic structures of strained‐layer superlattices (SLSs) (InAs)n(InP)n(001), (n=1–5) under three different strain conditions via a linearized muffin‐tin‐orbital method with two treatments fordstates. The effects of In 4dorbitals on the band structure and the valence band offset (VBO) are investigated. The hydrostatic pressure behavior and the &Ggr;–Xmixture in these SLS systems are also discussed. It is found that the band gap of the InP/InAs system is insensitive to its layer thickness. The VBO values at the SLS’s under the three strain conditions are determined by a frozen potential approach. Our results demonstrate that for the InP/InAs system the bulklike property is almost recovered in the molecular layer next to the interface. This behavior may be due to the common cation on both sides of the interface. This makes the frozen‐potential approach converge very fast with the layer thickness. Our results of band structure for the (1+1) SLS under a free‐standing mode are consistent with those given by a more elaborate full‐potential linearized augmented‐plane‐wave (FLAPW) calculation. The present results of VBO are about 0.07–0.09 eV larger than the data from an x‐ray photoelectron spectroscopy measurement and the FLAPW method, while in good agreement with the results given by the model solid theory. ©1995 American Institute of Physics.