The indications of mastectomy as opposed to the conservative surgery usually performed in patients with small breast cancers are discussed. They include true multifocal tumors, technical limitations, contraindications to radiation therapy (which is an indispensable adjunct to conservative surgery), and above all suspected multifocal tumors or residual tumor after partial excision. In these situations, it is of paramount importance to obtain high quality imaging and cytologic studies and to follow strict rules for surgical sampling. When there is a strong suspicion of residual tumor, there are a number of alternatives to total mastectomy, which are detailed herein. The place of extemporaneous examination is discussed.