A 38-year-old man developed symptoms of arthalgias and arthritis, lymphadenopathy, and weight loss. An axillary lymph-node biopsy was done in the diagnostic study; a periodic acid Schiff stain, done for evidence of fungal infection, showed periodic acid Schiff reagent-positive macrophages. Electron microscopy showed the typical morphologic features of the bacilliform bodies associated with Whipple's disease to be present in the macrophages of the lymph node. The patient had no intestinal symptoms. The absorption of a variety of substrates was found to be normal. Nine intestinal biopsies showed no organisms similar to those found in his lymph node. On tetracycline therapy, he symptomatically improved. The findings raise the question of the route of infection in Whipple's disease and point up the usefulness of periodic acid Schiff staining of lymph-node biopsies.