Two children aged two and two and a half years were admitted on account of seizures. It was discovered that the seizures were due to badly maintained gas water heaters but not until after discharge of the children from hospital. Other symptoms in these children were pyrexial episodes, hyperreflexia and tachycardia. One of the children developed diffuse alopecia which may possibly have been due to exposure to carbon monoxide. Mild carbon monoxide poisoning frequently causes vague symptoms which resemble symptoms of virus infections and may therefore not be recognized. In cases where the main symptom consists of seizures in young children, the differential diagnosis from febrile convulsions and commencing epilepsy may be difficult.