Male breast cancer is rare compared to its female counterpart and makes less than 1% of all breast cancer. Its etiology is less known than that of female breast cancer. Numerous experimental and clinical studies indicate the possibility of an increased risk of male breast cancer in workers occupationally exposed to electromagnetic field, light at night, and high temperature. There are also studies, which reveal the increased risk of this disease induced by occupational exposure to pesticides, aromatic hydrocarbons and ionizing radiation. However, irrefutable epidemiologic data from prospective clinical trials have not yet been obtained.