Abstract: The unsteady temperature distributions on ultrahigh molecular weight polyethylene (UHMWPE) acetabular cup for artificial hip joint were calculated. The contact pressure distributions and related surface temperature changes on the surface of the UHMWPE acetabular cup with designed micro-ball texture were investigated and compared with those of an ideally smooth surface. It was found that the computed temperature for the ideally smooth surface was lower than the reported temperature determined experimentally, while the computed temperature for the surface with regular texture agreed well with the measured temperature reported elsewhere. Thus it was rational to take into account the surface texture in calculating the surface temperature of the UHMWPE acetabular cup in motion. Moreover, the friction coefficient, and load, and the swing of the hip joint all had effect on the cup surface temperature. Namely, the cup surface temperatures increased with increasing friction coefficient and load, and it oscillated periodically with the hip joint swinging.