The results of thirty-five joint (hip or knee) replacements in nineteen patients who had an organ transplantation were retrospectively reviewed. The patients received a standard immunosuppressive induction regimen at the time of the transplantation and were maintained on a combination of prednisone, azathioprine, and cyclosporine A. All patients received antibiotics perioperatively, but antibiotic-impregnated bone cement was not used for any procedure.Six joint replacements, in three patients who were an average of 48.2 years old at the time of the arthroplasty, were performed before a renal transplantation. Twenty-four joint replacements, in fourteen patients who were an average of 40.9 years old at the time of the arthroplasty, were performed after an organ transplantation. Two patients, who were an average of 53.8 years old at the time of the arthroplasty, each had a joint replacement both before and after a liver transplantation (a total of five joint replacements). The average duration of follow-up from the first joint replacement was 8.8 years (range, one to twenty-three years). The Harris hip score or The Hospital for Special Surgery knee score was determined at the time of the latest follow-up examination.An infection developed around the implant in five patients who had had the joint replacement after a transplantation. The average interval from implantation of the prosthesis until detection of the infection was 3.4 years (range, one to six years). One patient who had a liver transplant was infected with Pseudomonas aeruginosa and another one was infected with Escherichia coli. One patient who had a renal transplant was infected with Staphylococcus epidermidis; one, with Enterococcus; and one, with Serratia marcescens.We found that patients who had a joint replacement after an organ transplantation had a very high risk of devastating infection. The rate of such infection was 19 per cent (five of twenty-seven joint replacements in sixteen patients).