Background: Angiotensin I-converting enzyme (ACE) gene plays an important role in the pathogenesis of cancers. The association between ACE insertion/deletion (I/D) polymorphism and the risk of various cancers has been studied. However, the results of these studies remain conflicting. Therefore, we performed a meta-analysis to evaluate the association between ACE I/D polymorphism and the risk of cancers. Methods: PubMed, Embase, ScienceDirect, Springer, CNKI, Wanfang, Weipu, CBM databases and Google Scholar were searched for case-control studies on ACE I/D polymorphism and the risk of cancers, published up to Dec 31, 2013. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association between ACE I/D polymorphism and cancer risk. Results: Thirty-five published studies with 5007 cases and 8173 controls were included. Overall, there were no significant association between ACE I/D polymorphism and the risk of cancers (II vs. ID+ DD OR = 1.05, 95% CI = 0.89-1.23, I vs. D OR = 1.00, 95% CI = 0.89-1.13). However, when stratified by ethnicity, we found a significant association between this polymorphism and cancer risk in Caucasians (II vs. ID+ DD: OR = 1.43, 95% CI = 1.02-2.00, I vs. D: OR = 1.23, 95% CI 1.01-1.49). Conclusion: ACE I/D polymorphism is associated with the cancer risk in Caucasians.