For several years carbamazepine has been used to treat intractible mania and it is frequently used in combination with lithium. Reports of toxicity have appeared in the past 2 years and some risk factors have been suggested. This paper reports four cases of brain-damaged adolescents treated with carbamazepine and lithium for both seizure and behaviour control who developed this reported neurotoxic phenomenon.A neurotoxic syndrome has been reported in psychiatric patients receiving both lithium and carbamazepine for the control of bipolar illness [1,2]. Although these patients may represent a more commonly encountered population for the general psychiatrist, the use of psychotropic agents in neurologically impaired patients is common. In these patients, the competing needs of effective behaviour control, adequate seizure prophylaxis and minimum side-effects must be balanced. This paper describes four adolescents with brain injury who developed lithium–carbamazepine neurotoxicity when treatment for behavioural disorders coincided with anticonvulsant therapy.