Using reflection high energy electron diffraction and atomic force microscopy, the growth of Ga1-xInxP alloys on GaP (0 0 1) with x varying from 0.2 to 1 (InP) is investigated and compared to that of arsenides on GaAs (0 0 1) or InP (0 0 1). Ar 520 degreesC, the evolution of the critical thickness for 3D growth versus In content is rather similar to that observed in the GsInAs/GaAs system. For x less than or equal to 0.5, 3D growth leads to the development of wire-like structures along the [1 1 0] direction which can he related to recent results on the phophide surface reconstructions. Finally, for the growth of InP on GnP at 520 degreesC, the critical thickness is 2.1 MLs and we observe a small density of very large islands, in contrast to the InAs/GaAs case. At 400 degreesC, the critical thickness decreases (1.7 MLs) as well as the island mean size whereas the density increases, We discuss this behavior in terms of surface energy.