Background: Although the number of patients undergoing laparoscopy-assisted distal gastrectomy (LADG) has been increasing, there is no confirmatory randomized controlled trial (RCT) to evaluate the efficacy of LADG compared with open distal gastrectomy (ODG). Safety and short term outcome are presented. Methods: We conducted a RCT to confirm the non-inferiority of overall survival (OS) of LADG to ODG in patients with clinical IA (T1N0) or IB (T1N1 or T2 [MP] N0) gastric cancer. D1 or more dissection is applied for clinical stage IA and D2 dissection for clinical stage IB. Only the credentialed surgeons can be responsible for both procedures. The primary endpoint is (OS). The planned sample size was 920. Results: Between March 2010 and November 2013, 921 patients (LADG 462, ODG 459) were enrolled from 33 institutions. Operating time was longer in LADG than ODG (median 278 vs 194 min, p < 0.001). Blood loss was smaller in LADG than ODG (median 38 vs 115 ml, p < 0.001). There were no grade 3 or 4 intraoperative adverse events in either arm. There was no difference in the overall proportion of in-hospital, non-hematological grade 3 or 4 adverse events excluding biochemical data (3.3%: LADG, 3.7%: ODG). The proportion of grade 3 or 4 serum AST/ALT increased was higher in LADG than ODG (16.4% vs 5.3%, p < 0.001). The proportion of the patients who required an analgesic on postoperative days 5–10 was smaller in LADG than ODG (50.3% vs 59.3%, p = 0.006). The median time from surgery until the first episode of flatus was shorter in LADG than ODG (2 days vs 3 days, p < 0.001). There was no difference in both the highest body temperatures during the first 3 days after the surgery and the highest body temperatures during hospitalization. Conclusions: Although the elevation of serum AST/ALT should be taken care, this trial confirmed that LADG performed by the credentialed surgeons was safe as ODG in terms of adverse event and short-term clinical outcomes. LADG will be an alternative procedure in clinical IA/IB gastric cancer if the non-inferiority of LADG in OS is confirmed by the primary analysis planned in 2018. Clinical trial information: UMIN000003319.