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Background and aim: Given their poor prognosis, patients with residual disease (RD) in the re-resection specimen of an incidental gallbladder carcinoma (IGBC) could benefit from a better selection for surgical treatment. The Gallbladder Cancer Risk Score (GBRS) has been proposed to preoperatively identify RD risk more precisely than Tstage alone. The aim of this study was to assess the prognostic value of RD and to validate the GBRS in a retrospective series of patients. Material and methods: A prospectively collected database including 59 patients with IGBC diagnosed from December 1996 to November 2015 was retrospectively analyzed. Three locations of RD were established: local, regional, and distant. The effect of RD on overall survival (OS) was analyzed with the Kaplan-Meier method. To identify variables associated with the presence of RD, characteristics of patients with and without RD were compared using Fisher's exact test. The relative risk of RD associated with clinical and pathologic factors was studied with a univariate logistic regression analysis. Results: RD was found in 30 patients (50.8%). The presence of RD in any location was associated with worse OS (29% vs. 74.2%, p = 0.0001), even after an R0 resection (37.7% vs 74.2%, p = 0.003). There was no significant difference in survival between patients without RD and with local RD (74.2% vs 64.3%, p = 0.266), nor between patients with regional RD and distant RD (16.1% vs 20%, p = 0.411). After selecting patients in which R0 resection was achieved (n = 44), 5-year survival rate for patients without RD, local RD, and regional RD was, respectively, 74.2%, 75%, and 13.9% (p = 0.0001). The GBRS could be calculated in 25 cases (42.3%), and its usefulness to predict the presence of regional or distant RD (RDRD) was confirmed (80% in high-risk patients and 30% in intermediate risk p = 0.041). Conclusion: RDRD, but not local RD, represents a negative prognostic factor of OS. The GBRS was useful to preoperatively identify patients with high risk of RDRD. An R0 resection did not improve OS of patients with regional RD.