Although age has been studied as a prognostic factor in breast cancer, little attention has been paid to its role in the selection and outcome of local therapy. A review of 42 breast cancer patients less than 40 years of age treated at the University of Chicago from 1989 to 1992 demonstrated that of women with stage 0, I, or II disease, 37% had medical contraindications to breast preservation compared with 25% of women over 40. Twenty-one percent of young women eligible for conservation opted for mastectomy and reconstruction compared with 9% of their older counterparts. Only 4% of women in either age group selected mastectomy alone as therapy. The literature on the relationship of age to local failure after breast conservation and the long-term morbidity of the local therapy of breast cancer is reviewed. Further research to clarify issues in local therapy in young patients is proposed.