We evaluated the results of treatment for ninety-seven patients (106 infections in ninety-eight hips) who had had either an infection after a total hip arthroplasty or positive intraoperative cultures of specimens obtained during revision of a total hip arthroplasty for presumed aseptic loosening. The patients were managed according to various protocols on the basis of the clinical setting (positive intraoperative cultures, early postoperative infection, late chronic infection, or acute hematogenous infection). Aerobic gram-positive cocci accounted for 109 (74 per cent) of the 147 microbial isolates; gram-negative bacilli, for twenty-one (14 per cent); and anaerobes, for twelve (8 per cent). The white blood-cell count and erythrocyte sedimentation rate were elevated in association with seventeen (16 per cent) and sixty-seven (63 per cent) of the 106 infections, respectively.The mean duration of follow-up was 3.8 years (range, 0.3 to eleven years). A good result was noted after the initial treatment of twenty-eight (90 per cent) of the thirty-one infections that had been diagnosed on the basis of positive intraoperative cultures at the time of the revision, twenty-five (71 per cent) of the thirty-five early postoperative infections, twenty-nine (85 per cent) of the thirty-four late chronic infections, and three of the six acute hematogenous infections. Of the twenty-one infections for which the initial therapy failed, twelve eventually were eradicated after additional treatment and the hip had a functional prosthesis at the time of follow-up. Of the ninety-seven infections that were treated successfully (there was a functional retained or exchange prosthesis in place at the time of the most recent follow-up and infection had not recurred at least two years after the discontinuation of antibiotic therapy), nine were associated with subsequent aseptic loosening of the prosthesis. The factors associated with recurrent infection were retained bone cement, the number of previous operations, potential immunocompromise, and early postoperative infection after arthroplasty without cement.