An isolated axillary lymph node metastasis in a woman without an obvious clinical primary site most frequently originates from the breast. Mastectomy has been the historical treatment of choice. A retrospective study of 35 patients was undertaken to evaluate the roles of modern mammography, breast preservation, and adjuvant systemic therapy in the management of these patients. Twenty-eight patients underwent a mastectomy, while 7 were managed by a combination of limited resection and/or axillary dissection and radiation therapy. Twenty-two (67%) of the 33 breast specimens contained carcinoma. Comparison of the pathologic results with the preoperative mammograms showed a specificity of 73%, while the sensitivity was only 29%. Actuarial 5-year survival after mastectomy or breast preservation was similar (77% and 65%, respectively). Patients with more than one positive lymph node benefited from adjuvant therapy. Mammography does not locate the majority of occult stage II breast cancers, and both breast preservation and adjuvant therapy may have roles in the management of these patients.