Although epilepsy is particularly common among people with intellectual disability (ID) it remains unclear whether it is associated with an increased likelihood of co-morbid psychopathology. We therefore investigated rates of mental health problems and other clinical characteristics in patients with ID and epilepsy (N = 156) as compared to patients with ID but no epilepsy (N = 596). All participants were consecutive referrals to specialist mental heath services. Specialist clinicians agreed on the mental health diagnoses by applying ICD-10 clinical criteria using information gained from interviews with key informants and the patients. Bivariate and multivariate analyses showed that patients with epilepsy were more likely to live in residential housing and have severe ID in line with previous evidence. However, the presence of epilepsy was not associated with an increased likelihood of co-morbid psychopathology. On the contrary, rates of mental health problems, including schizophrenia spectrum, personality and anxiety disorders, were significantly lower among patients with epilepsy. The results are discussed in the context of mood-stabilizing and other psychotropic effects of anti-epileptic drugs in adults with ID and epilepsy, as well as possible diagnostic overshadowing. (C) 2010 Elsevier Ltd. All rights reserved.