We have successfully grown ferromagnetic-metal (MnAs)/III-V semiconductor (GaAs, AlAs, InAs)/ferromagnetic-metal (MnAs) trilayer heterostructures on GaAs(1 1 1)B substrates by molecular beam epitaxy. In magnetoresistance (MR) measurements in current-in-plane (CIP) geometry, the spin valve effect was clearly observed, which was caused by the change of the magnetization of the two ferromagnetic MnAs layers between parallel and antiparallel directions. All the trilayer structures showed peculiar temperature dependence of the MR, which is very different from the conventional all-metallic magnetic multilayers. The MR ratio was found to be larger with decreasing the thickness and decreasing the energy band Sap of the semiconductor spacer layer.