The aim of this study was to examine the comorbidity pattern, seizure characteristics, and aetiology in a representative group of children with a combination of autism spectrum disorder (ASD), active epilepsy, and learning disability. Ninety children (47 males, 43 females; mean age 11 years 2 months, range 8 to 16 years at the time of psychiatric examination) with active epilepsy and learning disability, identified in a population-based study in Göteborg, Sweden, were subdivided into those with and those without ASD and compared with respect to aetiology, additional neuroimpairments, and seizure characteristics. In addition, the cohorts were examined for trends of prevalence over a period of time. Results indicated that established aetiology was much more often present in the prenatal period than in the peri- or postnatal periods in the ASD group. Cerebral palsy and visual impairment were under-represented in the ASD group. Partial seizures tended to be more common and generalized seizures less common in the ASD group compared with the non-ASD group. Seizure onset was later in the ASD group. Many of the significant differences were accounted for by a large group of psychiatrically unclassifiable participants in the non-ASD group. There was no trend towards an increase of affected children over the 12-year period. There was no increase in the prevalence of active epilepsy and learning disability nor in the rate of autism with active epilepsy and learning disability in children born between 1981 and 1986 compared with those born from 1976 to 1980, indicating no statistical association with the general measles-mumps-rubella vaccination introduced in the early 1980s.