International audience ; Mutations in the breast cancer susceptibility genes , , and are known risk factors for female breast cancer. Mutations in and also are associated with male breast cancer (MBC). Similarly, it had been suggested in the original identification report that the 1100delC mutation confers an increased risk for MBC. Here, we have evaluated the risk of 1100delC for MBC by genotyping 1100delC in 23 familial and 71 unselected Dutch MBC cases. None of the 23 familial MBC cases carried the 1100delC mutation. In contrast, 1100delC was present in 3 of the 71 (4.2%) unselected MBC cases, which was significantly more prevalent than the 1.1% Dutch population frequency assessed in 1,692 individuals ( = 0.05, OR = 4.1, 95% CI 1.2–14.3). Our data suggest that, in the Netherlands, 1100delC is associated with an increased risk for MBC.