Four of 184 ceramic femoral heads that the authors used in total hip arthroplasty fractured from 5 to 9 months after surgery. A polyethylene-lined acetabular component was used in all cases. The fracture rate, 2.2%, was much higher than previously reported for ceramic head fractures when used with a polyethylene cup. The fractures occurred during normal daily activities. Possible causes included manufacturing defects, neck length (short in all cases), bearing diameter (28 mm in all cases), cone-trunnion mismatch, excess hoop stresses from impaction, or material deterioration. All patients were treated by removal of debris, wide excision of capsular tissue containing tiny abrasive fragments, exchange of the modular polyethylene liner, and implantation of a cobalt-chrome femoral head. The trunnion had been somewhat damaged by relatively brief exposure to the ceramic particles in every case. The authors' experience suggests that ceramic femoral heads be used with caution.