The 10-to-13 year performance of 307 Mallory Head cementless tapered total hip replacements in 283 patients was assessed. Eighty-five percent of patients had a diagnosis of osteoarthritis. Fifty-one percent of patients were women. The mean patient age was 64 ± 10 years. The Hex Loc cementless acetabular component and titanium alloy femoral heads were used in each patient. At final followup, 37 (13%) patients died, 32 (10%) had revision surgery, and two (1%) were lost to followup. No femoral stem was revised for aseptic loosening, but one was revised because of sepsis and one was revised because of a periprosthetic fracture. Wear, osteolysis, and loosening were problems with the Hex Loc cementless acetabular components and 31 (10%) acetabular components required revision because of these mechanisms. The mean Harris hip score at final followup of the remaining patients was 87 ± 14 points. Three percent of these patients had thigh pain. Radiographic assessment revealed that no femoral stem or acetabular socket was definitely or probably loose. Three-dimensional wear assessment using the Devane technique was 0.35 mm per year. The Mallory Head cementless, tapered femoral component performed well in the patients in the current study, but unfortunately, the clinical results were compromised by the use of a suboptimal cementless acetabular component, the use of polyethylene that was gamma-irradiated in air, and by the use of titanium alloy femoral heads. Future developments obviously will be in the areas of better acetabular component design, alternate polyethylene sterilization methods, and enhancements of the femoral stem in terms of offset choices, neck design, and perhaps ingrowth surface.