We have succeeded in growing monocrystalline ferrimagnetic Mn2Sb thin films on (001) GaAs by molecular-beam epitaxy. From the reflection high-energy electron and x-ray diffraction patterns, the orientation of Mn2Sb films grown on (001) GaAs substrates was found to be with the c axis 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.