BACKGROUND AND AIMS: Endoscopic Submucosal Dissection (ESD) enables en bloc resection of large colorectal neoplasms, but the recurrence risk with positive or indeterminate horizontal margins (HM1/x) remains debated. This meta-analysis evaluated the local recurrence rate following en bloc ESD with HM1/x margins. METHODS: A systematic search of PubMed, EMBASE, Web of Science, and Cochrane Library through June 2024 identified studies reporting local recurrence after colorectal en bloc ESD with HM1/x margins. Cases with positive or indeterminate vertical margins (VM1/x) or histological high-risk features were excluded. Cumulative incidences and odds ratios (ORs) were pooled using mixed-effects logistic regression. RESULTS: Eleven studies with 441 HM1/x primary resections (331 benign, 12 invasive, 98 unknown) were included. The pooled recurrence rate was 4.3% (20/441; 95%-CI, 2.5%-7.5%). Median time to recurrence was 14 months (range: 6-71). Histological details were available for 16 recurrences (3 invasive, 13 benign). Two invasive recurrences originated from invasive lesions; the third from a high-grade dysplasia (HGD) lesion. Treatment of recurrence was reported for 10 cases, with 7 undergoing endoscopic resection (all benign) and 3 surgery (1 benign IBD-related lesion, 2 invasive). The recurrence risk was significantly higher for HM1/x margins compared to negative horizontal margin (HM0) cases (5/1655 vs. 15/403; OR 8.04; 95%-CI, 2.77-23.30). CONCLUSIONS: En bloc ESD with HM1/x margins is associated with a significantly higher risk of local recurrence compared to HM0 resection. However, the absolute risk remains low and most recurrences are benign. As invasive recurrences seem to originate from initially invasive or HGD lesions, intensive surveillance should be prioritized for HM1/x cases with these characteristics, rather than all HM1/x cases.