We have grown ferromagnetic MnAs thin films on InP(0 0 1) substrates by low-temperature molecular beam epitaxy (MBE) and investigated their structural and magnetic properties. We found that the MnAs c-axis (MnAs[0 0 0 1]) lies along the InP [(1) over bar 1 0] axis, and the easy magnetization axis lies in-plane, along the MnAs [11(2) over bar 0] axis, which is parallel to the InP[I 10] axis. The Curie temperature of the MnAs films on InP(0 0 1) was estimated to be 321 K. We have also grown the ferromagnetic MnAs on In0.65Ga0.35As0.75P0.25 thin films, and their structural and magnetic properties were very similar to those of the MnAs thin films directly grown on InP(0 0 1). The feasibility of growing monocrystalline ferromagnetic layers on InP(0 0 1) will open up the possibility of the monolithic integration of magnetic devices with InP-based optoelectronics. (c) 2006 Elsevier B.V. All rights reserved.