The case of a 60-year-old man who had an enlarging thigh mass seen during a routine 12-year examination of a cementless revision total hip arthroplasty is presented. Aspiration of the mass yielded more than 200 cc of thick yellow fluid. Cytopathologic examination disclosed material consistent with polyethylene wear debris. The porous titanium acetabular and femoral components were not loose. Reoperation was recommended despite minimal symptoms, because the fluid-filled mass recurred after aspiration. At the time of reoperation, the components appeared well fixed and a linerhead exchange was performed. One year after surgery, the mass had not recurred and the patient had minimal symptoms.