A multicentric randomized trial evaluated the interest of internal mammary dissection on operable breast cancer patients. One thousand four hundred and fifty‐three patients were included in the study and were followed for ten years. There is no difference in survival or in relapse‐free survival between the two groups. There were significantly more local recurrences in the group without internal mammary dissection, but these recurrences occurred mainly on patients who developed metastases. A great difference between centers was observed in the number of nodes examined and there is therefore a difference in the prognostic value of the number of nodes invaded. Copyright © 1983 American Cancer Society