Epidemiological studies have evaluated the association between ATM C.1066-6T > G (IVS10-6T > G) mutation and breast cancer risk. However, the results remain conflicting rather than conclusive. In order to derive a more precise estimation of the relationship, we performed this meta-analysis. Systematic searches of PubMed and Medline databases were performed. A total of 11 studies including 8,831 cases and 4,957 controls were identified. The carrier frequency of the ATM C.1066-6T > G mutation was 0.5% (45/8,831) in patients with breast cancer and 0.7% (38/4,957) in healthy controls. When all the 11 studies were pooled into the meta-analysis, there was no evidence for significant association between C.1066-6T > G mutation and breast cancer risk (OR 0.87, 95% CI 0.55-1.37). In the subgroup analyses by source of controls and family history with BRCA1/2 status, no significant association were found in any subgroup of population. When sensitivity analyses were performed, all the results were not materially altered. In summary, the meta-analysis strongly suggests that ATM C.1066-6T > G mutation is not associated with increased breast cancer risk.