Summary: Purpose: To determine the incidence, etiology, and prognosis of acute symptomatic seizures in children by age 3 years.Methods: In a population-based birth cohort study of all 15,209 neonatal survivors born in Tainan City between October 1989 and December 1991, parents or caretakers of 13,493 children aged 3 years were surveyed by telephone regarding any provoked convulsive disorder, particularly acute symptomatic seizure, in the children; medical records were reviewed.Results: Sixty-three children (39 boys, 24 girls) had acute symptomatic seizures (incidence 0.46 in 100). The leading causes of acute symptomatic seizures were acute gastroenteritis, encephalitis/encephalopathy, and bacterial meningitis. Agespecific incidence was highest in the group aged 1-12 months. Intracranial hemorrhage, bacterial meningitis, and metabolic disturbance were the major causes of acute symptomatic seizures in children aged 1-12 months. Acute gastroenteritis, encephalitis/encephalopathy, and bacterial meningitis accounted for 85% of the causes in children aged 13-24 months, and gastroenteritis and encephalitislencephalopathy were the predominant causes in those aged 25-36 months. By age 5 years, subsequent unprovoked seizures developed in 14% of the survivors of acute symptomatic seizures.Conclusions: Many acute symptomatic seizures are preventable. The risk of subsequent unprovoked seizures is determined by underlying precipitating factors. Public education regarding the danger of shaken-baby syndrome and excessive water supplement, as well as and nationwide vaccination against bacterial meningitis in young children, is necessary. Key Words: Acute symptomatic seizure-Children.Convulsive disorders represent one of the most common neurological problems in children. Most occur before age 3 years because the causes (fever, metabolic disturbance, head trauma, CNS infection and acute encephalopathy) occur predominantly in early childhood (1,2), Reports indicated that the incidence of epilepsy and unprovoked seizures was focused in industrialized countries (1)(2)(3)(4)(5). In most epidemiological studies, acute symptomatic seizure disorders are usually studied in association with epilepsy, and few such studies have focused on children (3,6,7). In the present study, the incidences, etiology, and prognosis of acute symptomatic seizures in children at age 3 years were investigated in a geographically defined area of southern Taiwan.