The wear rate of ultra-high molecular weight polyethylene total hip replacement components is known to be influenced by various factors such as material and design. However, it is not known if these factors affect the size or morphology of the wear particles. The aim of this study was to compare the polyethylene wear particles from hip replacements of differing bearing materials and designs. Tissues were obtained at the revision surgeries of patients with surface replacements with titanium alloy or cobalt-chrome alloy femoral components up to 51 mm in diameter, and stem-type hip replacements with cobalt-chrome or alumina ceramic femoral components that were 28 or 32 mm in diameter. The polyethylene particles were isolated following tissue digestion and density gradient separation, and then studied by scanning electron microscopy. A computerized image analysis system was used to measure the diameter and length of the particles. The majority of wear particles were submicron in diameter. No systematic differences in size and morphology were found between the groups in this study. The similarity in size and morphology of the wear particles suggested that the same basic wear mechanisms were occurring in these components.