In this report the author presents the results of a study of axillary lymph node involvement in 46 radical mastectomy specimens. The average number of lymph nodes per case was 22.7, with the central group of nodes the most numerous. Most of the lymph node metastases were located in this central group. Seventy-three per cent of the patients who had clinically palpable lymph nodes had actual metastases. The incidence of axillary lymph node metastasis among the entire group was 48 per cent.