PURPOSE:All types of trauma to the organism produce a systemic response that is proportional to the severity of the lesion caused. The more rapid clinical recovery during the postoperative period of patients undergoing laparoscopic‐assisted colectomyvs.patients receiving conventional surgery suggests that laparoscopic surgery produces less surgical trauma. The aim of this randomized, prospective study was to compare acute phase postoperative response in patients diagnosed with colon neoplasm undergoing open segmentary colectomyvs.laparoscopic‐assisted colectomy.METHODS:From June 1994 to July 1997 the results of 97 patients (58 submitted to open colectomy and 39 undergoing laparoscopic‐assisted colectomy) were analyzed. Blood determinations of cortisol, prolactin, C‐reactive protein and interleukin‐6 were performed before surgery and at 4, 12, 24, and 72 hours after surgery.RESULTS:The plasma levels of cortisol and prolactin were higher in the postoperative period with both surgical techniques with no significant differences being observed. The levels of interleukin‐6 achieved a maximum peak at 4 hours after surgery, later showing a decrease and practically achieving basal levels at 72 hours in both groups. The levels of interleukin‐6 were higher with significant differences at 4, 12, and 24 hours in the patients undergoing open colectomy. The plasma levels of C‐reactive protein were significantly lower at 72 hours in patients receiving laparoscopic‐assisted colectomy.CONCLUSIONS:The results obtained in this randomized, prospective study suggest that acute phase systemic response is attenuated in patients undergoing laparoscopic‐assisted colectomy in comparison with patients receiving open colectomy.