Psychosocial and sexual disturbances are common sequelae to a diagnosis of breast cancer and its treatment. The intuitively plausible hope that the advent of breast conserving techniques would prevent the psychological distress experienced following mastectomy has not been realised. Studies comparing psychosocial outcome of mastectomy with lumpectomy and radiotherapy reveal some advantage to women treated with breast conserving procedures in terms of body image, but very little difference in terms of psychiatric morbidity or sexual dysfunction. Whatever the primary therapy, women must still confront the fact that they have had cancer, a life-threatening disease which may recur. In this chapter the research comparing psychological outcome between mastectomy and lumpectomy is critically reviewed and the implications that these data have for clinical practice are discussed.