Laparoscopic cholecystectomy has rapidly become established as the treatment of choice for cholecystolithiasis. There is very little evidence, however, to support the claimed benefit to patients. In the present study 30 consecutive patients below the age of 65 years without acute cholecystitis and with no signs of common bile duct stones were randomized to laparoscopic or conventional open cholecystectomy. Median (interquartile range) intravenous consumption of pethidine with a patient-controlled injection device between 13 and 24 h after surgery was 125 (62-175) mg in patients who underwent the laparoscopic procedure and 200 (150-250) mg in those who had open operation. Urinary adrenaline and cortisol levels as well as those of plasma glucose, C-reactive protein and interleukin 6 were increased after surgery in both groups of patients, but without any significant difference between them. The mean(s.d.) duration of postoperative hospital stay (2.8(0.8) versus 1.8(0.6) days) and sick leave (24.0(4.4) versus 11.7(4.1) days) was significantly longer with open than laparoscopic cholecystectomy. The findings demonstrate obvious advantages of laparoscopic surgery as regards postoperative pain and convalescence, although factors reflecting the magnitude of trauma did not differ.