Abstract The relative stability of wurtzite, zinc‐blende, rock‐salt and CsCl structures and the possibility of high‐pressure phase transformations from wurtzite to rocksalt and from rocksalt to CsCl is of special interest. We present a comparative study of the stability of these phases for two Group IIIB‐nitrides (ScN, YN) and two Group IIIA‐nitrides (GaN, InN), in the framework of DFT. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)