ZnSe is a semiconductor with a direct band gap of 2.68 eV at room temperature, which makes it one of the most important materials for blue electroluminescent devices and short wavelength laser diodes. In this communication, heteroepitaxial growth of ZnSe on a GaAs/Si substrate by low‐pressure organometallic chemical vapor deposition is reported. The ZnSe/GaAs/Si epilayer exhibits a uniform surface morphology. Strong photoluminescence near‐band‐edge emission was observed. The thickness of the GaAs buffer layer seems to be an important factor in the energy shift of the photoluminescence peak.