Prolactin secretion after tonic-clonic seizures (10 patients), complex partial seizures (five) and non-epileptic attacks (three) was studied in a group of children aged between 0.3 and 14 years. Seven patients with other subcategories of seizure disorders were also studied. Eight children with tonic-clonic seizures exhibited post ictal concentrations of prolactin greater than 500 mU/l. One of the children, who responded on one occasion, did not do so on another. Three children with complex partial seizures had post ictal prolactin concentrations greater than 500 mU/l, while in two the increased values were more modest (390 mU/l and 420 mU/l). The timing of the peak post ictal prolactin concentration varied from less than 20 minutes to a prolonged plateau for three hours. Other seizure types--simple partial with motor signs (2), absence seizure (1), myoclonic seizure (1), minor epileptic status (3) (with one exception), and non-epileptic attacks (3) were not associated with post ictal concentrations greater than 500 mU/l.