Considering the high morbidity in young individuals, the authors reviewed 73 Charnley total hip arthroplasties in patients under age 40. The average follow-up period was 6.6 years. A total of 22 hips failed. Thirty-one hip arthroplasties were performed in normally ambulatory patients, with nine failures. Forty-two were performed in patients with limited locomotion, with 13 failures. The main cause of failure was loosening requiring revision (ten hips). There was radiologic evidence of progressive loosening in four other hips. Loss of trochanteric fixation required revision of six hips. Activity and rheumatoid disease were major contributing factors. Alternative methods of treatment should be considered in the young patient. When the operation is indicated, the greater trochanter must not be removed. It is hoped that cementless methods of fixation may produce a lower incidence of failure.