Breast pain, also known as mastalgia, is a common condition and affects up to 70% of women during their lifetime. Mastalgia is classified as cyclical, noncyclical, or extramammary. Cyclical mastalgia is the most common type of breast pain and is characterized by discomfort that is most prominent during the luteal phase of ovulation, improving with menses. Noncyclical mastalgia has no relationship to the menstrual cycle and is more common among women in their fourth or fifth decades of life. Causes of noncyclical mastalgia include duct ectasia, mastitis, large breast size (with stretching of Cooper ligaments), medications, pregnancy, thoracic vein thrombophlebitis, trauma, or prior breast surgery. Although uncommon, advanced breast cancer, invasive lobular carcinoma, and anaplastic carcinoma of the breast may also present with mastalgia. Extramammary mastalgia is caused by pain that is referred from other anatomic locations, including the chest wall, heart, gallbladder, or spine.