The recurrence and five year disease-free survival rates of 86 patients with carcinoma of the breast located in the medial quadrants who had either lumpectomy and radiotherapy or mastectomy were compared. Patients who had lumpectomy and mastectomy were comparable with respect to variables reflecting extent of the disease. One of 54 patients who had lumpectomy had a local recurrence and five had a recurrence regionally or at distant sites. In the group of 32 patients who had a mastectomy, one patient had a local recurrence and an additional four patients had a recurrence at other sites. The five year study disease-free survival rate was 83 per cent for the lumpectomy group and 78 per cent for the mastectomy group. These data suggest that, for medial quadrant lesions, there may be a disease-free survival advantage associated with lumpectomy and radiotherapy over mastectomy. Further study of this treatment modality for this subset of patients seems indicated.