We report the results of a 4-to 17-year clinical and radiological follow-up of 264 Charnley first-generation stems in comparison with those of 402 second-and subsequent-generation stems. The incidence offracture was 4.1% in first-generation stems and 0.5% in second-and subsequent-generation stems. The incidence of stem loosening requiring or likely to require revision was 3.1% in first-generation and 11.4% in second-generation stems. We believe that the increased loosening rate in second-and subsequent-generation stems is due to their larger crosssectional area, which produces an increase in flexural stiffness.