It is not easy to make diagnose FCHL in children, since a clear expression of lipoprotein abnormality is unlikely and standard criteria have not yet been established. We investigated eight cases of childhood FCHL and their families with respect to familial history, anthropometric parameters and serum lipoprotein levels, to explore the characteristics of childhood FCHL. To diagnose childhood FCHL it is necessary to clarify both the family history and lipid profiles of the parents. In this study, two prominent features were suggested; that serum TG level is affected by both obesity and age, and also in particular, that a significantly elevated level of serum apoB is a predominant feature of FCHL in childhood. It was found that hyperapoB may be revealed antecedently without other lipid abnormalities at an early age. Regardless of other lipoprotein abnormality, it was suggested that hyperapoB might be added to the early diagnostic criteria for FCHL.