Objective This study analyzed the UHMWPE insert wear in total hip replacement of different prosthesis designs and wear conditions. Methods Specimens of acetabular cups were selected among the total hip prosthesis revisions at Mackay Memorial Hospital, Taipei, during the years from 1993 to 2003. The specimens included products of DePuy-AML? Plus series, Mecron-Mecring series and Osteonics-Omnifit series, which were of totally different designs. This study focused on differentiating the wear among these three types of products. In our study, the wear score was defined as the severity factor (determined by the wear pattern) × the amount present (determined by the worn area). The number was multiplied by a severity factor assigned to each wear pattern on a scale of 0-7. A classification system was designed which identified the following eight pattern of damage on the surface: burnishing, abrasion, deformation, scratching, pitting, delamination, wear-through and component fracture. In each region the severity of each pattern was graded on a scale of 0-3, based on the percent area of the region affected, to give a total cumulative wear score for each UHMWPE insert. We inspected the UHMWPE insert with light stereomicroscopy to measure worn area and to classify the wear pattern. The wear scores thus calculated were analyzed to demonstrate the difference in wear related to designsof components in the types of hip prostheses. Results The most common types of wear observed, abrasion (100%), wear-through, component fracture (40%), scratching (36%) and burnishing (33%). Multiple linear regression analysis was used to determine possible associations between wear score and the patient’s gender, age and weight at the time of the operation, the duration that the implant had been in situ. It was found no relationship between any clinical variable and the visually evaluated wear score. There was a significant positive correlation between the wear score and the angle of the inclination of the cup. Conclusion Clinical variables have little influence on polyethylene wear of well functioning hip replacements. Alternatively, it may be related to the variety of cup designs included in our study.