Yellow nails occurred in six patients. One patient had, in addition, severe lymphedema, a pleural effusion, and persistent hypoalbuminemia. In view of the clinical association of this nail disorder with edema, lymphatic structure and function have been studied in these patients. Lymphangiograms were performed on four patients but abnormalities were noted only in the one patient with severe lymphedema. A test of dermal lymphatic function of the nail regions using clearance values for injected iodinated I 131 serum albumin was also performed. The clearance of the iodinated albumin was slightly less than in a group of 23 other patients, but the difference was not statistically significant. Skin biopsies were performed in four patients but no morphological abnormalities of the small vessels were detected.