The observations made during the treatment of 120 chronic alcoholics with Antabuse are reported. Certain animal experiments are also described.1. In large doses Antabuse is toxic to animals. Death by respiratory arrest is preceded by an ascending paralysis. The Antabuse in these large doses produces liver, spleen, kidney, and C.N.S. damage.2. In human subjects, large doses produce gastro-intestinal and nervous symptoms. In therapeutic amounts there are no apparent effects on liver, kidney, blood, heart, or brain. Patients should not be given Antabuse until at least 4 days have elapsed since their last alcoholic debauch.3. In rats a moderate dose of Antabuse markedly increases the toxicity of ethyl alcohol.4. In patients on Antabuse therapy a definite pattern of reaction may be seen after a test dose of alcohol. This syndrome, subjectively and objectively, is much like that observed after the ingestion of a large quantity of alcohol at one time. Cardiovascular collapse may result. Supportive therapy and intravenous ascorbic acid may abort the syndrome. There is an increased blood acetaldehyde during the reaction.5. The selection of patients for therapy must be on an individual basis. The patient must be willing to take the drug. He should have no organic disease that might endanger his life if he should imbibe a small amount of alcohol.6. A test dose of alcohol is given each patient to determine the effectiveness of the Antabuse, and to give him the startling experience of becoming violently intoxicated on a very small amount of alcohol.7. Intensive psychotherapy must be employed in the management of the alcoholic on Antabuse. The patient's family and friends and the A. A., social agencies, and others should be called upon for the rehabilitation of the patient.8. Each Antabuse patient should carry a clinic card indicating that he is on Antabuse therapy, SO that if he should drink and have a reaction, emergency therapy may be started if required. Some experiences with such "slips" are described.9. Of the 120 patients reported in this paper, 74 are improved. The initial "cure" rate was much higher. Most slips occurred at 3 months. The question is raised whether a test dose should be given every 3 months.10. It is most important that the drug be administered under careful medical psychiatric supervision. Indiscriminate use of Antabuse by the private practitioner without the aid of a therapeutic regime, hospital or clinic, and without psychiatric consultation is to be condemned.