We report the growth of TlGaAs on（001）GaAs substrates by molecular beam epitaxy. X-ray diffraction measurements showed resolved peaks of Tl_x，Gal_<1-x>As epitaxial layers and GaAs substrates for the samples grown at substrate tempratures of 400-450℃. The peak separation of 30 are sec observed in the X-ray rocking curves indicates the existence of Tl_xGa_<1-x>As epitaxial layers having Tl contents around x＝0.0016.