Through the analysis of the common apolipoprotein (apo) E gene polymorphism in large Caucasian population study with the PCR and subsequent restriction analysis, we have identified carriers of mutant allele Arg136-->Ser. Both of them (71-years-old female and her 43-years-old son) have normal lipid parameters. We suggest that Arg136-->Ser mutation in apoE is not necessarily connected with elevated lipid levels in all cases. Furthermore, so far unidentified factors (environmental and/or genetic) are important for the development of lipid metabolism disorders in apoE Arg136-->Ser mutation carriers.