During the period 1969 through 1974, 716 total hip-replacement arthorplasties were performed. The results of the surgery in 275 cases of rheumatoid arthritis as regards complications were compared with those in 382 procedures in cases of osteoarthritis. In contrast to the reports of others,the incidence of deep would infection in the two groups was found to be equal. Patients undergoing total hip-replacement arthroplasty as a revision of a previous operation had a substantially increased risk of infection. Patients with rheumatoid arthritis, however, were more subject to certain other complication (intraoperative fracture, difficulties with anesthesia, and malposition of prosthetic components), in addition to the complications that were predictable because of the involvement of multiple joints and the systemic disease process.