In our initial study with patients having hepatolenticular degeneration, we confirmed the results of Cummings and Denny-Brown that BAL markedly increases the urinary excretion of Cu. These patients excrete much smaller amts. of Cu via the stools than do the normals. There is also a marked difference in the urinary excretion. Patients with Wilson''s disease are usually in a marked positive Cu balance. There is evidence that these people absorb much more Cu through the intestinal wall than do normal subjects and excrete it mostly through the urine. Patients were also given a Na polystyrene sulfonate resin, and this resin bound the Cu and removed it through the stool. On a normal diet a negative Cu balance was obtained both in patients with Wilson''s disease and in the normal subjects. It is suggested that the increased intestinal absorption of Cu in hepatolenticular degeneration may account for the increased storage of Cu found in this disease. An exchange resin may prove to be a less severe type of treatment and may prove to be more effective.