Fifty consecutive unselected patients with infiltrating carcinoma of the breast underwent radical mastectomy in two consecutive stages. The initial operation was a modified radical mastectomy, with preservation of the pectoral muscles, and the second stage, a procedure to transform the initial operation into a standard radical mastectomy. An analysis of the location and the number of the lymph nodes recovered in the two stage operation shows that a so-called modified radical mastectomy is inadequate to ensure the clearing of the axilla. Lymph nodes were recovered at the second stage of the operation in 36 patients, and seven of these patients had metastasis. Modified radical mastectomy was effective in eradicating the lymph nodes of the lower part of the axilla but inadequate for lymph nodes at levels II and III and, especially, the interpectoral lymph nodes.