Data from two epidemiological studies are used to measure the degree to which two well-known guidelines agree in measuring hyperlipidemia in population samples in the US and Poland. The epidemiological studies are the US Lipid Research Clinics Program Prevalence Study and the Pol-MONICA project in Poland and the guidelines are those adopted by the US National Cholesterol Program (USNCEP) and by the European Atherosclerosis Society (EAS). EAS guidelines were analyzed in two ways: Method 1 used triglycerides and total cholesterol only in classifying persons as hyperlipidemics or non-hyperlipidemics; Method 2 used triglycerides, total cholesterol and nine additional risk factors in the classification process. USNCEP guidelines used total cholesterol, low density lipoprotein cholesterol and the same additional nine risk factors used in EAS Method 2 in classifying hyperlipidemics. Classification differences between the two sets of guidelines were high when EAS Method 1 guidelines were compared with USNCEP guidelines. However, EAS Method 2 which included risk factors, compared favorably with USNCEP guidelines in all three populations under study.