The case of a patient with yellow nail syndrome (YNS), an infiltrating duct carcinoma of the breast, and giant cell interstitial pneumonitis (GIP) is presented. YNS has not been previously described in association with GIP. There was improvement of the yellow fingernails following surgery and chemotherapy for the breast cancer. The possible pathogenesis of the yellow nails in this case and its management are presented. A wide variety of conditions are associated with YNS, which has been reported to respond to various treatment modalities. The most likely cause in our case is impaired lymphatic drainage. However, treatments that do not affect lymphatic drainage also have been reported to be successful.