We have succeeded in growing monocrystalline ferrimagneticMn2Sbthin films on (001) GaAs by molecular-beam epitaxy. From the reflection high-energy electron and x-ray diffraction patterns, the orientation ofMn2Sbfilms grown on (001) GaAs substrates was found to be with thecaxis normal to the surface. This direction is also the easy magnetization direction as determined by superconducting quantum interference device measurements at room temperature. Magneto-optical spectra of these films showed a much larger magneto-optical Kerr effect than bulk data from the infrared to the blue wavelength region. ©1997 American Institute of Physics.