The objective demonstration of improved postoperative recovery suggests that the surgical injury response induced by the laparoscopic approach is less intensive than that after open surgery. Twenty-five patients diagnosed as having noncomplicated gallstones were studied prospectively. They were operated by laparoscopy (group I, n = 12) or open surgery (group II, n = 13). Analgesia requirements (p < 0.026) and postoperative stay (p < 0.001) were significantly less in group 1. Cholecystectomy performed by either technical options induced a significant increase over basal values of glucose, lactate, white blood cell count, prolactin, ACTH, cortisol, interleukin 6, C-reactive protein, and PCO2. Both surgical procedures induced a significant reduction of total proteins, albumin, prealbumin, free fatty acids hemoglobin, hematocrit, and pH. There were no differences between the levels of growth hormone, insulin, glucagon, or PO2 during any of the periods studied. Comparison of the results of the two cholecystectomy techniques showed that laparoscopic cholecystectomy induced a significantly less intensive acute-phase response (area under the curve) of interleukin 6 (17 +/- 17 versus 47 +/- 26 pg/ml x hr x 10(2); p < 0.003), C-reactive protein (16 +/- 12 versus 35 +/-16 mg/dl x hr x 10; p < 0.004), and prealbumin (16 +/- 2.7 versus 13.8 +/- 2.3 mg/dl x hr x 10(2); p < 0.05). The surgical injury response after laparoscopic cholecystectomy is similar to that after open cholecystectomy, but the aeute-phase response component is less intense. This finding may be a consequence of the reduced size of the operative wound with laparoscopic cholecystectomy.