401 patients scheduled for total hip arthroplasty were randomized to one of three groups of bearing surfaces: an oxidized zirconium (OxZi) femoral head on a highly crosslinked polyethylene liner (OxZi-XLPE), an OxZi femoral head on an ultra-high molecular weight polyethylene liner (OxZi-UHMWPE), or a cobalt chromium (CoCr) femoral head on a XLPE liner (CoCr-XLPE). The purpose of this study was to compare wear, incidences of osteolysis and aseptic loosening, and functional outcomes between the three groups at mid-term follow-up. At 5 years, the groups which received the XLPE liner (OxZi-XLPE and CoCr-XLPE) demonstrated significantly lower steady-state wear compared to the OxZi-UHMWPE. There was no significant difference in wear between the OxZi-XLPE and CoCr-XLPE groups.