To determine the safety of laparoscopy-assisted distal gastrectomy (LADG) compared with open distal gastrectomy (ODG) in patients with clinical stage I gastric cancer in Korea. There is still a lack of large-scale, multicenter randomized trials regarding the safety of LADG. A large-scale, phase 3, multicenter, prospective randomized controlled trial was conducted. The primary end point was 5-year overall survival. Morbidity within 30 postoperative days and surgical mortality were compared to evaluate the safety of LADG as a secondary end point : A total of 1416 patients were randomly assigned to the LADG group (n = 705) or the ODG group (n = 711) between February 1, 2006, and August 31, 2010, and 1384 patients were analyzed for modified intention-to-treat analysis (ITT) and 1256 were eligible for per protocol (PP) analysis (644 and 612, respectively). In the PP analysis, 6 patients (0.9%) needed open conversion in the LADG group. The overall complication rate was significantly lower in the LADG group (LADG vs ODG; 13.0% vs 19.9%, P = 0.001). In detail, the wound complication rate of the LADG group was significantly lower than that of the ODG group (3.1% vs 7.7%, P < 0.001). The major intra-abdominal complication (7.6% vs 10.3%, P = 0.095) and mortality rates (0.6% vs 0.3%, P = 0.687) were similar between the 2 groups. Modified ITT analysis showed similar results with PP analysis. LADG for patients with clinical stage I gastric cancer is safe and has a benefit of lower occurrence of wound complication compared with conventional ODG.