1. In dogs, Antabuse decreases glomerular filtration.2. Dogs tolerate Antabuse without evidence of liver damage.3. Giving of Antabuse to dogs did not alter their response to paraldehyde.4. An intravenous infusion of acetaldehyde in dogs causes a depression of the R wave in all leads in the electrocardiogram.5. The regularity of the estrous cycle in rats is not affected by Antabuse.