In simulator studies, the Biolox-forte hip prosthesis were run for 5 million cycles (Mc) using 50% new born calf serum for both the standard test (STD) mode and the micro-separation test (MSX) mode. Wear measurements were carried out every 0.5 Mc. The wear patterns were mapped and observed by SEM. In a clinical study, the OstealTM hip prostheses which were implanted for 15 to 19 years and 17 year BioloxTM hip prostheses were analyzed. According to the same technique as the simulator study, the wear patterns were analyzed using SEM. The steady-state wear rates for alumina THR ranged from 0.16 to 0.65 mm3/Mc in the MSX mode and 0.011 mm3/Mc in the STD mode. The MSX simulator mode produced two narrow wear scars (stripes) of dull appearance on the ball. In the SEM analysis, the stripe scars showed mild wear after 5 Mc duration. In the Biolox and the Osteal retrieval alumina ball, the stripe scars showed severe wear. The Osteal retrievals had one grade lower wear in the main worn area than the Biolox retrievals on SEM analysis. The stripe wear and its location in the retrieval balls were seen in the simulator study. The area and wear severity of the stripe wear were influenced by the quality of alumina, design of THA and various actual motions in patients.