Objective: To study the relationship between epilepsy and aggression in a population of severely mentally handicapped people. Methods: Comparing epilepsy and aggression variables in people with epilepsy without aggression, people with aggression without epilepsy, and people with both. The epilepsy variables were: seizure frequency, classification, anticonvulsant drugs, therapeutic drug monitoring, and neuroleptic drugs. Aggression variables were: frequency, direction, type, and neuroleptic drugs. Results: Prevalence of aggressive behaviour was similar in people with and without epilepsy (36%). Partial seizures were less prevalent in people with epilepsy and aggression. People with epilepsy were more likely to manifest unprovoked aggression directed against property. Conclusion: Some episodes of aggressive behaviour in people with epilepsy may be ictal in origin.