1. Clinical and chemical data on acutely intoxicated patients show a direct quantitative relationship of the patient's blood barbiturate levels to his clinical condition. 2. The "half-life" of phenobarbital, amobarbital, and pentobarbital was determined to aid in prognosis of an intoxicated patient with a given blood barbiturate level. 3. Urinary clearance studies showed that the clearance was directly proportional to the urine flow. 4. A patient's urine barbiturate level has no relation to his clinical condition.