Periodontal condition was studied in 84 epileptic 8-18 year-old patients who had been undergoing antiepileptic drug (AEP) treatment for a period of at least 3 years. They were diagnosed as suffering from partial seizures (simplex or complex) or general tonic-clonic fits and were treated with therapeutic oral doses of phenytoin (PHT) and carbamazepine (CBZ) or valproic acid (VPA) in mono- or polytherapy. All patients received a drug dosage to ensure adequate plasma concentration and satisfactory seizure control. The Gingival Index (GI), Sulcus Bleeding Index (SBI) and Plaque Index (Pl-I) were individually scored. The control group contained 30 age-matched healthy children and adolescents. The GI and SBI indices were higher in epileptics than in controls. Only the Pl-I was similar in both groups. Gingival enlargement was found in 30% of the epileptic patients. There was no definite plasma concentration-dependent increase in the incidence of gingival overgrowth.