In the last decade, laparoscopic procedures are applied to the treatment of almost all colonic diseases, including both benign and malignant lesions. Focusing our attention to the laparoscopic operative technique, we compare the perioperative results and the oncological outcomes of laparoscopic hemicolectomy with those after open conventional hemicolectomy. This prospective non randomized study is based on a series of 469 consecutive patients (73.6% with malignant lesions) operated on by the same surgical team following the same type of surgical technique, for laparoscopic and open approach, to perform right (RH) and left (LH) hemicolectomy, respectively, excluding segmental resections, emergency operations as well as transverse colon, splenic flexure and recurrent carcinomas. The treatment modality was selected by the patients after reading the informed consent form. Conversion rate to open surgery (for the laparoscopic group) and causes were assessed. Statistical significance (p) for operative time, resumption of gastrointestinal functions, length of stay, complications, perioperative mortality, as well as length of specimen, number of lymph-nodes harvest, incidence of local recurrences and distant metastases, and survival probability analysis in malignant cases, was assessed between the 2 groups (laparoscopic and open). From March 1992 to February 2003, 166 patients underwent RH and 303 LH. In the RH group, 108 patients underwent laparoscopic approach and 58 underwent open surgery (26 vs 13 for benign lesions and 82 vs 45 for adenocarcinomas, respectively). LH was performed by laparoscopy in 202 patients and by laparotomy in 101 (55 vs 30 for benign lesions and 147 vs 71 for adenocarcinomas, respectively). There were no conversions to open surgery in laparoscopic RH, while 10 patients (4.9%) in the laparoscopic LH group required conversion: 3 of 34 performed for diverticular disease and 7 of 147 performed for malignancy. Mean operative time for laparoscopic surgery was longer than for open surgery (182 vs 140 min for RH and 222 vs 190 min for LH, respectively), but with increasing experience this decreased significantly. Mean hospital stay in patients who underwent laparoscopic procedures was significantly shorter both in RH and LH groups (9.2 vs 13.2 days and 9.9 vs 13.2 days, respectively). Similar major complication rates were observed between the 2 laparoscopic and open groups (1.8% vs 1.7% for RH and 4.1% vs 4.9% for LH, respectively). Follow-up time ranged between 12 and 109 months (mean, 57.3 months) in RH groups and between 12 and 111 months (mean, 57.5 months) in LH groups. The follow-up dropout was of only 3 patients after RH (in the laparoscopic group) and 5 after LH (3 in the laparoscopic group and 2 in the open group). The local recurrence rate was lower after laparoscopic surgery in both arms (7% vs 8.8% for RH and 3.3% vs 7% for LH, respectively), but the differences were not statistically significant. Two port site recurrences were observed in the laparoscopic groups, 1 after a Dukes D palliative RH and 1 after a Dukes C LH converted to open surgery (1.7% and 0.9%, respectively). Metachronous metastases rates were similar between the laparoscopic and open groups (20.9% vs 17.6% for RH and 4.4% vs 5.3% for LH, respectively). Cumulative survival probability (CSP) at 72 months after laparoscopic RH was 0.791 as compared to 0.765 after open surgery (p=0.326) and 0.956 after laparoscopic LH as compared to 0.877 after open surgery (p=0.115). CSP for Dukes stage A, B and C in the laparoscopic RH group was 0.875, 0.846, and 0.727 as compared to 0.9 (p=0.815), 0.889 (p=0.87), and 0.6 (p=0.183) after open surgery, respectively. CSP for Dukes stage A, B and C in the laparoscopic LH group was 0.1, 0.966, and 0.885 as compared to 0.1 (p=0.936), 0.944 (p=0.466), and 0.7 (p=0.072) after open surgery, respectively. These results suggest that laparoscopic hemicolectomy for both benign and malignant lesions can be performed safely. Oncological outcomes were comparable with those of open surgery.