Deep sepsis occurred after fourteen (9 per cent) of 156 elbow-replacement procedures in 140 patients. This high frequency of infection was attributed to several factors. First, the patients were drawn from a population that was at high risk of infection, because rheumatoid arthritis and post-traumatic arthritis were the indications for arthroplasty. Second, many of the patients had had prior surgery, which significantly (p less than 0.02) increased the risk of sepsis in those with rheumatoid arthritis. Third, some patients had surgery after the arthroplasty, which also seemed to predispose to deep infection (p less than 0.05). In one patient the elbow was salvaged by early debridement, and in two others reimplantation of a total joint replacement was successful after removal of the first prosthesis and control of the infection. Resection arthroplasty was required to arrest the infection in ten patients, eight of whom had a satisfactory result. The high incidence of this significant complication attests to the hazardous nature of the elbow-replacement procedure and should warn orthopaedic surgeons to be cautious when recommending this form of treatment.