To determine whether some of the side effects of antiepileptic drugs could be due to zinc depletion within tissues, zinc concentrations in the polymorphonuclear leucocytes in 26 epileptic patients receiving valproate or carbamazepine and 14 controls were assessed. There was no difference in zinc concentration in leucocytes among the three groups and no evidence of zinc depletion. Valproate and carbamazepine may affect the intracellular distribution of zinc.