Two cases of fatal hepatic damage in patients receiving phethenylate ("thiantoin") sodium are reported, and the possible hepatotoxic effect of this drug is discussed. In both patients, a 44-year-old woman and a 6-year-old boy, there was no evidence of infectious disease when the acute hepatic failure developed. Both had been receiving phethenylate for about five months for the control of convulsive seizures, and, while homologous serum hepatitis cannot be excluded definitely, it appears that the phethenylate contributed to the development of the disease. REPORT OF CASES Case 1.— M. C., a 44-year-old white woman, was admitted to Germantown Hospital on May 25, 1950, complaining of jaundice. She had been taking phethenylate sodium, 0.2 gm. three times daily, for five months for control of petit mal seizures. Sixteen days before admission nausea and anorexia developed, and two days later vomiting occurred. On May 23 she first noted jaundice, dark urine, and