Purpose: Breast cancer is an important cause of cancer-related death in women. Numerous studies have evaluated the association between the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene and breast cancer risk. However, the specific association is still controversial rather than conclusive. Therefore, we performed a meta-analysis of related studies to address this controversy. Methods: PubMed, EMBASE, Google Scholar and the Chinese National Knowledge Infrastructure databases were systematically searched to identify relevant studies. A meta-analysis was performed to examine the association between the I/D polymorphism in the ACE gene and susceptibility to breast cancer. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. Results: 10 separate studies of 7 included articles with 10,888 subjects on the relation between the I/D polymorphism in the ACE gene and breast cancer were analyzed by meta-analysis, and our results showed no association between the I/D polymorphism in the ACE gene and breast cancer in total population and different populations. No publication bias was found in the present study. Conclusions: The ACE I/D polymorphism may not be associated with breast cancer risk. Further large and well-designed studies are needed to confirm this conclusion.