In a material of sudden, unexpected death of epileptic patients treated with one or more of the anticonvulsants phenobarbitone, phenytoin and carbamazepine we found subtherapeutic drug levels in half of the cases and lethal concentrations, mainly of phenobarbitone, in one third of the cases. The results illustrate the severe consequences of noncompliance in epilepsy, and stress the value of blood drug level control.