Serious complications after carbamazepine poisoning, such as coma, seizures, respiratory failure, cardiac conduction abnormalities, and death are more likely with serum levels greater than 170 micromol L(-1). We report a case of a single massive carbamazepine overdose in a 19-year-old male, following attempted suicide, without prior history of seizure disorder. On admission, three hours after ingestion, serum carbamazepine concentration was 179 micromol L(-1) and Glasgow Coma Scale scored 6. The patient was intubated and treated with multiple doses of activated charcoal for 48 hours. Twelve hours after ingestion, two repeated generalised myoclonic seizures were noted when serum carbamazepine levels peaked at 181 micromol L(-1), and were successfully treated with diazepam. Carbamazepine serum level fell within the therapeutic range 63 hours after ingestion and the patient was discharged without any long-term sequelae. As there is no antidote for carbamazepine poisoning, supportive treatment remains the only, but usually potent option.