The records of 716 consecutive patients with breast cancer randomized from January 1964 to January 1968 between radical and extended radical mastectomy not followed by postoperative radiation therapy were reviewed. Relapse and survival rates were related to different patterns with the intent to define, on clinical basis, the high-risk groups in whom systemic adjuvant treatment can be attempted. The 10-year relapse rate was 52.9% for the whole series. In patients with negative axillary nodes (N-) this finding was 27.9% compared to 75.5% for patients with positive nodes (N+ 1-3: 66.5%, N+ greater than 3: 83.6%). The relapse rate was also affected by concomitant involvement of internal mammary nodes (IMN): N- IMN+: 60%, N+ IMN+: 96.7%. The corresponding 10-year survival rates were as follows: 59.7% (total), 81.9% (N-), 39.6% (N+), 53.7% (1-3), 25.6% (greater than 3), 45.8% (N- IMN+), 20.5% (N+ IMN+). In N+ patients relapse and survival rates were directly proportional to the size of primary tumor, while this trend was not present in N- patients. Location of primary tumor as well as menopausal status showed no direct effect on relapse and survival. In both nodal groups the sites of first relapse were documented to occur preferentially in distant organs and tissues.