Laparoscopic surgery is often associated with complications which never occur in open conventional surgery. We investigated operative and postoperative complications in urological laparoscopic surgery. From February 1990 to November 1992, 91 laparoscopic operations were performed, including 62 varicocelectomies, 5 pelvic lymphadenectomies, 6 adrenalectomies, 5 simple nephrectomies, 2 radical nephrectomies, 1 staged Fowler-Stephens operation and 10 laparoscopies for cryptorchidism or other disorders. The patients ranged from 3 months to 77 years old. Nine (9.9%) of the 91 patients had complications associated with laparoscopic procedures and 4 (4.4%) of them had major complications. Pneumoextraperitoneum occurred in 3 patients. Two patients, who suffered from preperitoneal insufflation or pneumothorax associated with pneumomediastinum, failed to undergo laparoscopy. A small amount of scrotal emphysema developed in one patient, which subsided within 12 hours. Another patient, who underwent radical nephrectomy and para-aortic lymphadenectomy for left renal cell carcinoma, complained of symptoms due to persistent pneumoperitoneum and subcutaneous emphysema, which subsided 2 weeks after the operation. Respiratory acidosis caused by carbon dioxide absorption, which was difficult to be controlled, occurred in the other two patients; one was an adult male with reduced respiratory function and the other was a 1-year-and-8-month-old child. Bleeding during or after the procedure was another serious complication. Vena caval laceration occurred during right simple nephrectomy for pyonephrosis with renal calculi and was managed with laparotomy. Two patients, one after simple nephrectomy and the other after right adrenalectomy, suffered from postoperative bleeding about 300 ml through the penrose drain, which subsided following a bed rest.(ABSTRACT TRUNCATED AT 250 WORDS)