OBJECTIVE To determine the value of antibiotic prophylaxis for the prevention of infection following postoperative T-tube cholangiography. METHODS A prospective, controlled study. METHODS A tertiary care center. METHODS The role of antibiotic prophylaxis during postoperative T-tube cholangiography was prospectively evaluated in 164 patients. METHODS Sixty-two patients were administered antibiotic prophylaxis treatment (1 g of cephalothin sodium was infused intravenously 30 minutes before the procedure and 500 mg of cephalexin was given orally every 6 hours for 3 days after the procedure). Seventy-one patients were in the control group and did not receive antibiotic therapy. METHODS Complications and adverse reactions following postoperative T-tube cholangiography were recorded and compared between the two groups. RESULTS There was no significant difference between the groups in regard to age, sex, serum amylase level before T-tube cholangiography, white blood cell count, and liver function. The results of the bacteriologic culture specimens of the bile were also comparable between the groups. One patient who had received antibiotic therapy and one patient in the control group had fever (temperature, > 38 degrees C) and chills after the procedure. Two patients who had received antibiotic therapy and one patient in the control group had mild abdominal pain. These complications were treated conservatively without any event. No significant difference was found in the rates of complications and the success of postoperative T-tube cholangiography between the groups. CONCLUSIONS Routine antibiotic prophylaxis for the prevention of infection following postoperative T-tube cholangiography is not necessary under selected conditions.