Serum zinc and vitamin E concentrations were measured in handicapped children aged 4-17 years, treated (n = 32) and untreated (n = 13) with phenytoin and phenobarbital. The mean serum zinc levels were 81 +/- 16 and 82 +/- 7 micrograms/dl in the treated and untreated children, respectively. The difference was not significant between these two groups. Hypozincnemia (below 70 micrograms/dl), however, was found in 7 of the 32 treated patients and in none of the 13 untreated children. The serum vitamin E level was 0.58 +/- 0.18 mg/dl in the treated and 0.67 +/- 0.17 mg/dl in the untreated children, indicating significantly lower levels in the treated patients (p less than 0.005). A significant positive correlation was found between the serum zinc and vitamin E levels (r = 0.45, p less than 0.005). Thus, long-term use of anticonvulsants results in a vitamin E and zinc deficiency, which may produce several unfavorable problems in children.