390 patients undergoing total hip arthroplasty were randomized to receive either a ceramic-on-metal (CoM) or meta-on-metal (MoM) bearing. The purpose of this randomized controlled trial was to compare these two bearings in terms of the revision rate and metal ion levels at 50 months postoperatively. No significant differences were noted in the proportion of patients undergoing revision surgery or 5-year survivorship between groups. In the metal analysis, between 1 and 5 years postoperatively, the MoM group displayed increases in erythrocyte and serum cobalt and decreases in erythrocyte chromium, whereas the CoM group did not display significant changes in metal ions.