We conducted a study comparing patients receiving continuous subcutaneous administration of analgesia with self controlled analgesia system (CSAA group) with those receiving continuous epidural infusion (Epi group) for postoperative analgesia after abdominal surgery. Fourteen patients were randomized into two groups: CSAA group (n = 7) received 20 micrograms.h-1 of buprenorphine (Bu) subcutaneously with additional 20 micrograms of Bu using Baxter infusor BB+PCA; Epg group (n = 7) received continuous epidural infusion of 0.4 mg of Bu and 46 ml of 0.25% bupivacaine daily (16.7 micrograms.h-1 of Bu) using Baxter infusor 2 ml.h-1 type. In both groups, patients received supplemental 0.1 mg of Bu subcutaneously as needed. During 48-hour postoperatively, verbal descriptor pain scale, sedative scale, visual analogue scale, supplemental doses of Bu, and side effects were evaluated. There was no significant difference of verbal descriptor pain scale, sedative scale, visual analogue scale, and supplemental doses of Bu between CSAA group and Epi group. Total doses of Bu during the first 12 hours postoperatively (CSAA group: 0.37 +/- 0.08 mg, Epi group: 0.30 +/- 0.08 mg) were significantly more than those during other 12-hour period in both groups (P < 0.05). There was no severe side effect in both groups. We conclude that continuous subcutaneous administration of analgesic was effective for postoperative analgesia, and almost the same analgesic effect was obtained as compared with continuous epidural analgesia. We calculated that the adequate dose of Bu subcutaneously during early postoperative period to be about 30 micrograms.h-1 of Bu.