656 Background: The benefits of laparoscopic surgery (LAP) compared with open surgery (OP) have been suggested; however, the long-term survival of LAP for advanced CRC requiring CME is still unclear. We conducted a trial to confirm the non-inferiority of LAP to OP in terms of overall survival (OS). Favorable short-term complications and clinical benefits of LAP have already been demonstrated. Overall survival, the primary endpoint, and late post-operative complications are presented here. Methods: Only accredited surgeons from 30 Japanese institutions participated. Eligibility criteria included histologically proven CRC; tumor located in the cecum, ascending, sigmoid or rectosigmoid colon; T3 or deeper lesion without involvement of other organs; N0-2 and M0; tumor size =<8 cm; age 20-75 years. Patients with pathological stage III received adjuvant chemotherapy with fluorouracil plus leucovorin. The planned sample size was 1,050 patients with a power of 80%, a one-sided alpha of 5% and the non-inferiority margin of the hazard ratio (HR) as 1.366. Results: A total of 1,057 patients were randomized (OP 528, LAP 529) between October 2004 and March 2009. Conversion to OP was needed for 29 patients in LAP arm. 5-year OS was 90.4% (95% CI: 87.5-92.6%) in OP, and 91.8% (89.1-93.8%) in LAP. The non-inferiority of laparoscopic CME in OS was not demonstrated (HR: 1.06 [90% CI: 0.79-1.41(>1.366)], p=0.073). 5-year RFS was 79.7% (76.0-82.9) in OP and 79.3% (75.6-82.6) in LAP (HR: 1.07 [95%CI: 0.82-1.38]). Proportion of grade (G) 2-4 late complications was 22.6% (OP 12.5%, LAP 10.1%). Late complications (G2-G4) included constipations (OP 6.0%, LAP 4.4%), diarrhea (OP 2.9%, LAP 2.7%), paralytic ileus (OP 1.2%, LAP 1.7%), and bowel obstruction of small intestine (OP 3.1%, LAP 2.1%). Conclusions: The non-inferiority of laparoscopic CME in OS was not demonstrated for stage II, III CRC. However, since OS of both arms are almost identical and better than expected, laparoscopic CME is acceptable as a treatment option for stage II, III CRC. Clinical trial information: C000000105.