AIM: To perform a systematic review of incidental or unsuspected gallbladder(GB) cancer diagnosed during or after cholecystectomy. METHODS: Data in Pub Med, EMBASE, and CochraneLibrary were reviewed and 26 publications were included in the meta-analysis. The inclusion criterion for incidental GB cancer was GB cancer diagnosed during or after cholecystectomy that was not suspected at a preoperative stage. Pooled proportions of the incidence, distribution of T stage, and revisional surgery of incidental GB cancer were analyzed.RESULTS: The final pooled population comprised 2145 patients with incidental GB cancers. Incidental GB cancers were found in 0.7% of cholecystectomies p e r f o r m e d f o r b e n i g n g a l l b l a d d e r d i s e a s e s o n preoperative diagnosis(95%CI: 0.004-0.012). Nearly 50% of the incidental GB cancers were stage T2 with a pooled proportion of 47.0%(95%CI: 0.421-0.519). T1 and T3 GB cancers were found at a similar frequency, with pooled proportions of 23.0%(95%CI: 0.178-0.291) and 25.1%(95%CI: 0.195-0.317), respectively. The pooled proportion that completed revisional surgery for curative intent was 40.9%(95%CI: 0.329-0.494). The proportion of patients with unresectable disease upon revisional surgery was 23.0%(95%CI: 0.177-0.294). CONCLUSION: A large proportion of incidental GB cancers were T2 and T3 lesions. Revisional surgery for radical cholecystectomy is warranted in T2 and more advanced cancers.