Epidemiologic studies have indicated that vitamin D might play a protective role against breast cancer. Incidence of breast cancer and mortality rate considerably vary worldwide and reveal a geographic pattern. The lowest rates of breast cancer generally occur in countries close the equator. With increasing latitude reported breast cancer incidence and mortality rates also increase. A negative correlation between available sunlight and breast cancer death rates has been shown. Because sunlight exposure is a measure of vitamin D produced in the skin, it has been hypothesized that vitamin D formed in the skin may reduce the risk of breast cancer [1-3]. Breast cancer is the most frequent cause of cancer death in women in the western world. Many studies have tried to identify the casual factors responsible for the uncontrolled growth of the tumor cells. A variety of biochemical and genetic changes have been identified in breast carcinomas and have been found to be related to breast cancer growth.