IgA, IgG and IgM concentrations were determined in sera and nasal washings from 20 patients with epilepsy on single-drug treatment with carbamazepine, in 20 patients on single-drug treatment with phenobarbital and in 26 healthy subjects. There were no significant differences in immunoglobulin concentrations between the groups of patients and the controls. Symptoms of respiratory tract disease were recorded daily during 6 months both in patients and in controls. The mean number of days with symptoms from the respiratory tract was 38.5, 36.6 and 27.9 in the patients on carbamazepine, phenobarbital and the controls, respectively. The differences were not statistically significant. The individuals with the lowest immunoglobulin concentrations did not have more frequent symptoms of respiratory disease than those with higher immunoglobulin concentrations.