Chlorhexidine is better than povidone-iodine for skin preparation before intravascular device insertion or blood culture collection, but it is not known whether chlorhexidine is superior in reducing the colonization of continuous epidural catheters. Patients requiring an epidural catheter for postoperative analgesia were randomly assigned to receive skin preparation with 0.5% chlorhexidine ethanol (CE group) or 10% povidone-iodine (PI group) before catheter insertion. Using surgical aseptic techniques, catheters were inserted into either the lumbar or the thoracic epidural space. Gloves used at catheter insertion, swabs of insertion site skin and the catheter tip at catheter removal were qualitatively cultured. Of 70 randomly assigned patients, 62 were evaluable. The clinical characteristics of the patients and the risk factors for infection were similar in the two groups. Catheters were kept in place for 49±7 h (mean±SD). Seven cultures from gloves yielded microorganisms. In 1 case, the leak test of gloves was positive. Fifteen cultures of catheter insertion sites yielded microorganisms: 7/28 (25%) in the PI group and 8/34 (24%) in the CE group. Six cultures of catheter tips yielded microorganisms: 3/28 (11%) in the PI group and 3/34 (9%) in the CE group. As for the incidence of isolation of bacteria, no difference was seen between the two groups. In none of these 62 cases was any inflammatory reaction seen in the skin locally at catheter removal. The effect of 0.5% chlorhexidine ethanol is not different from that of 10% povidone-iodine in reducing catheter colonization associated with short-term epidural catheter placement.