Epilepsy occurs in 15-60% of children with cerebral palsy; however, its clinical course is not well defined. This retrospective study reviewed the prevalence, nature, and prognosis of epilepsy in cerebral palsy. Thirty-two of 85 children with cerebral palsy seen in the Neurodevelopmental Clinic in Tuen Mun Hospital between 1990 and 1995 had epilepsy. A control group of 59 epileptic children with normal neurodevelopment status was seen during the same period. Epilepsy most commonly affected patients with spastic tetraplegia and those with mental subnormality. When compared with controls, children with cerebral palsy had a higher incidence of epilepsy with onset within the first year of age (47% vs 10%), history of neonatal seizures (19% vs 3%), status epilepticus (16% vs 1.7%), polytherapy (25% vs 3%), and treatment with second-line antiepileptic drugs (31% vs 6.7%). They had a lower incidence of generalized seizures (28% vs 59%) and remaining seizure free (37% vs 90%). Factors associated with a seizure-free period of 1 year or more in epileptic children with cerebral palsy were normal intelligence, single seizure type, monotherapy, and spastic diplegia. Epilepsy was common in children with cerebral palsy. Further larger studies are required to delineate other prognostic factors.