MnSb and MnSb-Mn2Sb mixed layers were grown on GaAs(100), (111)A and (111)B substrates by hot-wall epitaxy under various growth conditions. It was found that Sb/Mn flux ratio affected the orientation of MnSb layers grown on GaAs( 100). The crystalline quality of MnSb layers grown on GaAs(111) depends on the growth conditions, such as substrate temperature, Sb/Mn Aux ratio and substrate polarity. The crystalline quality of the layers on GaAs(111)B was superior to that of the layers on GaAs(111)A. The quality of the layers on GaAs(111)B, however, was steeply degraded as increasing Sb/Mn flux ratio. The Mn2Sb domains were generated in the layers grown on GaAs(111) substrates at high substrate temperature.