Radiographic, gross, and histopathologic studies on 158 whole breasts with primary operable carcinoma revealed intramammary lymph nodes in 28%, and of these breasts, 10% contained a metastatic deposit of carcinoma. Cancerous and noncancerous nodes were found in all quadrants of the breast with the positive ones being in the same quadrant as the carcinoma only 50% of the time. There was no demonstrable connection with the usual lymphatic drainage of the breast. With Stage II carcinoma, positive intramammary lymph nodes had no direct effect on prognosis, merely representing advanced disease and indicating a greater likelihood of axillary metastatic disease. There was a trend toward poorer prognosis in Stage I lesions with positive intramammary lymph nodes. This may indicate the Stage I carcinomas that have a similar prognosis as Stage II tumors. Conceivably, a Stage Ia, positive intramammary lymph node(s) but normal axillary lymph nodes, could be defined and used.