Phetharbital (Pyrictal), a barbiturate with virtually no hypnotic side effects, was originally introduced for the management of epilepsy and has since been shown to have powerful hepatic enzyme-inducing properties. In preliminary clinical studies, phetharbital was found to be effective against febrile seizures, minor myoclonic seizures and in petit mal. Phetharbital is relatively ineffective in the control of the tonic extensor seizure pattern and would not be expected to modify grand mal tonic seizures. Chronic administration of phetharbital causes an increased excretion of 6 beta-hydroxycortisol in human urine. This increase in 6 beta-hydroxycortisol excretion is not accompanied by an increase in the 17-hydroxycorticosteroids levels in urine, indicating that an increased adrenal output of cortisol is not responsible for the increased urinary levels of 6 beta hydroxycortisol. Phetharbital was also effective in the rare severe unconjugated hyperbilirubinemia of the Crigler-Najjar syndrome.