OBJECTIVES: Endoscopic submucosal dissection (ESD) allows en-bloc resection of the entire lesion which permits higher curative resection rate, lower local recurrence, and consequently, increases quality of life by minimizing the resection size compared to Endoscopic Mucosal Resection (EMR). While ESD has been implemented in most university hospitals in Korea currently, potential complications of ESD like haemorrhage and perforation waver over the therapeutic decision on the ESD for early gastric cancer patients as well as the reimbursement decision-making. The study aims to address both effectiveness and safety outcomes of ESD versus EMR in early gastric cancer by systematic review. METHODS: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Koreamed were searched using primary key words: ‘stomach neoplasm’ AND ‘endoscopic submucosal dissection’ AND ‘endoscopic mucosal resection’. To assess the quality of selected studies, the methodological approach of Scottish Intercollegiate Guidelines Network were used. Five effectiveness-relevant and three safety-relevant outcome measures were extracted. Bibliography management and meta-analysis for each outcome were conducted using Review Manager 5.0. RESULTS: Three non-concurrent cohort studies and nine retrospective cohort studies were identified. Meta-analyses showed significantly greater effectiveness of ESD as compared to EMR for en-bloc resection (OR=8.43, 95%CI: 5.20-13.67), complete resection (OR=8.54, 95%CI: 4.44-16.45), curative resection (OR=2.56, 95%CI: 1.68-3.91), local recurrence (RR=0.13, 95%CI: 0.04-0.40), and all-cause mortality (RR=0.65, 95%CI: 0.08-5.38). While intraoperative bleeding (RR=2.16, 95%CI: 1.14-4.09) and perforation risk (RR=3.58, 95%CI: 1.95-6.55) were significantly greater for ESD, overall bleeding risk (RR=1.22, 95%CI: 0.76-1.98) and longer resection time (RR=1.55, 95%CI: 0.74-2.37) were not significantly different between ESD and EMR. CONCLUSIONS: Considering bleeding risk was not significantly different between ESD and EMR, and the perforation risk usually does not lead to life-threatening disease, the effectiveness benefit of ESD can overweigh the overall harm compared to EMR on condition that ESD was performed by surgeons with certain experiences.