During a scheduled visit to the school physician, the number of children with a history of febrile seizures was determined in 3570 children attending primary schools in the suburban area of the city of Rotterdam. At the age of 6 years, 140 had experienced at least one febrile seizure (3.9%, 95% confidence interval 3.3% to 4.5%). Of these, 19 (14%) had experienced a recurrent seizure during the same febrile illness. Recurrent seizures in subsequent fever episodes occurred in 26%. The median age at onset was 18 months. One-third of the children had visited the hospital directly after the seizure, and 6% had used anticonvulsant drugs for at least 6 months. Of all the children, 5.4% had a positive first-degree family history of febrile seizures. Children with a positive family history were at a 4.5-fold increased risk of experiencing febrile seizures. Since in this study a generally accepted definition of febrile seizures was used, the estimated prevalence in Dutch school-children may well be compared with prevalence rates found in the United States and Great Britain.