Thirty pediatric cases of carbamazepine overdoses were reviewed retrospectively for the frequency of toxic effects. Patients were divided into three groups, depending on the type of overdose: acute, acute-on-chronic, and chronic. Effects included lethargy in 93%, ataxia in 50%, nystagmus in 13%, and minor arrhythmias in 10%. Major effects included seizures in 20%, coma in 27%, and need for intubation in 20%. Higher serum carbamazepine levels were associated with these major effects in the acute and acute-on-chronic groups but not in the chronic group. Serum levels greater than 35 mg/L (147 mumol/L), were significantly associated with major toxicities.