Adenine as a free base or mixed with NaH2PO4.H2O was given orally, in daily doses of 400-500 mg., to 3 dogs for 1-3 wks. Blood pressure dropped; weakness increased. Death occurred and gross autopsy findings included: alopecia, emaciation, glossitis, gingivitis, stomatitis, congested liver, submucosal hemorrhages in the duodenum, marked congestion in the jejunum and ileum, mottling of the kidney surface, and hemorrhages in the medulla. When dogs were given a daily dose of 300 mg. of adenine alone for 21 days, the signs and symptoms did not develop as fast as when phosphate was added. In addition, these dogs showed spasticity of the jaw muscles and extremities. At autopsy there were, in addition, hemorrhages in the esophagus and colon, very extensive hemorrhages in the small intestine, and slight edema in the walls of the gastrointestinal tract. Similar results were obtained in young albino rats. The syndrome produced by adenine points to multiple avitaminosis. It shows all the symptoms described in exptl. pellagra in dogs. Adenine may combine with constituents of the vitamins or their precursors, thus preventing their utilization. The expts. demonstrate a direct relation between purine metabolism and avitaminosis.