We report a rare finding of two male breast cancer patients with HER2-positive breast cancer who also developed thyroid cancer. We reviewed 45 male breast cancer patients treated in our institution from 2003 to 2008. Only five male breast cancer patients were HER2-positive. In reviewing the published data, we found no cases of thyroid cancer and concurrent breast cancer in men. However, breast cancer and thyroid cancer have shown close association in women. This finding therefore provokes speculation as to whether we should investigate whether women with HER2-positive breast cancer are at a higher risk for thyroid cancer. Although this observation seems to be clinically prevalent, publications are sparse in clinical research areas linking thyroid cancer to breast cancer.