Twenty-nine cases were reviewed in which carcinoma manifested first as the enlargement of an axillary node from an occult breast carcinoma. A small hidden breast cancer was identified in 16 patients. In the remaining 13, the breast tumor was never discovered. Regardless of whether the primary tumors were discovered, the metastasis-free survival rates were comparable to those of patients with breast carcinoma with axillary nodal metastasis. The authors recommend that carcinoma found in an axillary node should be treated as a breast cancer, even in the absence of the breast tumor. Extensive investigative procedures in an attempt to uncover an extramammary primary site were largely unproductive and should either be omitted or performed selectively. Mammography, if positive or suspicious, can lead to the primary tumor in 75% of the patients, but, when negative, it does not necessarily exclude the breast as the source of the carcinoma. A carcinoma of the breast was found by pathologic examination in 44% of the patients with negative mammograms.