Breast diseases present in six common ways — as a painless or painful lump, pain and tenderness but no lump, nipple discharge, changes in the nipple and areola and change in breast size, which this chapter describes through a table. The common causes of a painless lump are carcinoma, fibroadenoma, cyst and nodularity (fibroadenosis). This chapter describes the various types of diseases associated with the breasts and the process to examine them for proper diagnosis. An accurate examination of regional lymph nodes is important for staging of the breast cancer and prognosis. When palpating the lymph nodes, the examiner must assess the number, size, consistency and mobility of the lymph nodes. Axillary lymph nodes are enlarged and palpable in infections and malignancy of breast. Apart from the women, males also may have breast diseases. The common causes of enlargement of the male breast are gynecomastia and carcinoma. Breast lumps are rare in men. Carcinoma of the male breast constitutes approximately merely 1 percent of all breast carcinomas.