The lymph nodes of the internal mammary chain represent a primary station draining the lymph from the breast and their removal or their irradiation has been considered an important step in breast cancer treatment. From January 1964 to January 1968, 737 patients with breast cancer were randomised at the National Cancer Institute in Milan to undergo either Halsted mastectomy or extended mastectomy with internal mammary node dissection. Patients with non-disseminated carcinoma classified as T1, T2, T3, N0, N1 were eligible for the study. No patients received postoperative radiotherapy or systemic therapy. After 30 years of follow-up, the overall survival curves and the specific survival curves do not show any difference between the patients of the two groups. Among the 558 patients who died in the 30 year interval period, 395 (71%) died from breast carcinoma (201 in the Halsted group and 194 in the extended mastectomy group) and 163 from other causes. This study shows that the removal of internal mammary nodes does not improve the survival of patients treated for breast carcinoma. This finding supports the theory that treatment of regional nodes does not influence the survival of cancer patients. The prognostic value of internal mammary node status is, however, high and a biopsy on a selected lymph node should be considered for staging purposes.