Of 4171 total knee arthroplasties that were performed at our institution from 1973 to 1987, sixty-seven were followed by infection. The risk of infection was significantly increased in patients, particularly men, who had rheumatoid arthritis; in patients who had ulcers of the skin; and in patients who had had a previous operation on the knee. Infection was also associated with obesity, recurrent urinary-tract infection, and oral use of steroids, although the correlation was not statistically significant. Of the various treatment options that were studied, removal and delayed replacement of the knee prosthesis resulted in the best functional results.