Intrapleural bupivacaine has been reported to be effective for analgesia following cholecystectomy and thoracic surgery. Twenty patients who had a posterolateral thoracotomy were studied in a randomized, double-blind, placebo-controlled fashion. Patients were assigned to receive intrapleural administration of either 0.5 percent bupivacaine or saline solution every 4 h for 12 doses postoperatively, as well as narcotic analgesics as needed for additional pain control. Pain was assessed using a visual analogue scale. Narcotic analgesic use, duration of hospitalization, and the development of complications were recorded. There were nine evaluable patients who received bupivacaine, and ten patients who received placebo. The age, sex, and type of operation were similar in the two groups, and the procedures were performed by the same two surgeons. The mean pain score at 24 h postoperatively was 5.8 +/- 0.8 in the bupivacaine group and 6.0 +/- 0.6 in the placebo group. At 48 h, the scores were 4.6 +/- 0.8 in the bupivacaine group and 5.1 +/- 0.9 in the placebo group. The mean dose of morphine sulfate or equianalgesic dose of meperidine during the first 24 h was 13.9 +/- 3.7 mg in the bupivacaine group and 12.6 +/- 1.8 mg in the placebo group, and during the next 24 h it was 40.0 +/- 13.4 mg in the bupivacaine group and 38.0 +/- 9.2 mg in the placebo group. The mean duration of hospitalization was 12.8 +/- 3.2 days in the bupivacaine group and 12.1 +/- 2.9 days in the placebo group. Two patients who received bupivacaine and three patients who received placebo had development of pneumonia or atelectasis postoperatively. There was no statistically significant difference in any parameter between those who received bupivacaine and those who received placebo. Thus, there was no subjective or objective clinical benefit of this method of postoperative analgesia compared with placebo following posterolateral thoracotomy.