Results after 184 primary and 227 revision total hip arthroplasties were compared with an emphasis on rates of failure leading to reoperation and intra- and postoperative complications and on the clinical outcome of the nonrevised arthroplasties in the two series. The failure rate was 7% (11 of 156) in the primary series, versus 27% (54 of 195) in the revision series. The rate of complications was substantially higher after revision, due to 16% (36 of 227) intraoperative fractures of the femoral shaft and 6% (14 of 227) postoperative dislocations. Clinical assessment of the nonrevised arthroplasties in the two series revealed no difference with regard to relief of pain. For patients with concomitant disabling conditions functional outcome was inferior after revision, but for patients without such conditions the functional results of the two series were equal. The favorable clinical results of the nonrevised arthroplasties in the revision series must be seen in relation to the very high rate of failure leading to reoperation.