The purpose of this study was to screen for FCHL in children using serum lipid phenotypes. The subjects were 1190 (599 male, 591 female) children who participated in a screening and care program for life style-related diseases in school children. Total cholesterol, high-density lipoprotein cholesterol and triglyceride were determined, and information on the family history of parents was obtained by questionnaire. Candidates for FCHL were screened by the following criteria; type IIb hyperlipidemia, type IIa hyperlipidemia with positive family history of CHD, hyperlipidemia or both. We informed them of the results by mail. A second series of examinations to diagnose FCHL was performed on volunteer participants, including their parents. The candidates consisted of 9 children with type IIb and 27 with type IIa hyperlipidemia, 11 of whom participated, in the second series of examinations, in which 5 children were diagnosed with FCHL. The prevalence was 0.4%, suggesting that at least half of all individuals with FCHL already demonstrate hyperlipidemia in childhood.