['High-density lipoprotein (HDL) cholesterol is a powerful cardiovascular risk factor. Important gender and ethnic differences in plasma HDL levels exist and warrant investigation.', 'Cross-sectional survey in two different general populations. Patients 7700 participants of the National Health and Nutrition Examination Survey (NHANES) 1999-2002 and 1944 participants of the Hong Kong Cardiovascular Risk Factor Prevalence Study-2 (CRISPS2) 2000-2004.', 'Plasma HDL levels.', 'Plasma HDL levels were higher in women than in men in both populations. In the United States women, it increased with age, whereas in Chinese women, it declined with age and converged with male HDL levels. In the United States, 37.1 +/- 1.2% men and 38.9 +/- 1.1% women had low HDL levels. In Hong Kong, 34.3 +/- 1.6% men and 34.5 +/- 1.5% women had low HDL levels. In Americans, the independent predictors of low HDL levels were lower age, being non-Mexican Hispanic, waist circumference, triglycerides and not drinking alcohol in men, and lower age, being Hispanic, waist circumference, triglycerides, current smoking and not drinking alcohol in women. In Hong Kong Chinese, the independent predictors of low HDL levels were body mass index, triglycerides, current smoking and not drinking alcohol in men, and lower age, waist circumference, triglycerides, diabetes and former smoking in women.'] Do high density lipoprotein-cholesterol levels increase with age in American women but not in Hong Kong Chinese women?