BACKGROUND & AIMS: Simulation-based training (SBT) in gastrointestinal endoscopy has been increasingly adopted by gastroenterology fellowship programs. However, the effectiveness of SBT in enhancing trainee skills remains unclear. We performed a systematic review with a meta-analysis of published literature on SBT in gastrointestinal endoscopy. METHODS: We performed a systematic search of multiple electronic databases for all original studies that evaluated SBT in gastrointestinal endoscopy in comparison with no intervention or alternative instructional approaches. Outcomes included skills (in a test setting), behaviors (in clinical practice), and effects on patients. We pooled effect size (ES) using random-effects meta-analysis. RESULTS: From 10,903 articles, we identified 39 articles, including 21 randomized trials of SBT, enrolling 1181 participants. Compared with no intervention (n = 32 studies), SBT significantly improved endoscopic process skills in a test setting (ES, 0.79; n = 22), process behaviors in clinical practice (ES, 0.49; n = 8), time to procedure completion in both a test setting (ES =, 0.79; n = 16) and clinical practice (ES, 0.75; n = 5), and patient outcomes (procedural completion and risk of major complications; ES, 0.45; n = 10). Only 5 studies evaluated the comparative effectiveness of different SBT approaches; which provided inconclusive evidence regarding feedback and simulation modalities. CONCLUSIONS: Simulation-based education in gastrointestinal endoscopy is associated with improved performance in a test setting and in clinical practice, and improved patient outcomes compared with no intervention. Comparative effectiveness studies of different simulation modalities are limited.