Administration of taurine to a cat suffering from naturally occurring chronic (about 3 years) epilepsy caused disappearance of the clinical manifestation of the seizures as well as a marked improvement in the previously grossly abnormal EEG. The treatment consisted of injections of taurine initially, followed by a more prolonged administration of the amino acid by mouth. The combined methods of administration seemed essential for the success of the trial. To date (5 months post-taurine) the animal has suffered only one "grand mal" type seizure which occurred 3 months after the last dose of taurine was administered. Disappearance of the seizures preceded by several weeks the improvement in the EEG. In accordance with previous findings by a number of investigators, the results of this study suggest an immediate depressant action of taurine on hyperexcitable cortical neurons, followed by a more long-lasting, ameliorative influence on cerebral metabolism contributing to an increased resistance to epileptic discharge.