Background Low levels of high-density lipoprotein cholesterol (HDL-C), as well as high levels of low-densi-ty lipoprotein cholesterol, play a crucial role in the development of cardiovascular disease, which has shown a remarkable increase in Korea. Method and Results Data were obtained from the 1998 Korean National Health and Nutrition Examination Survey, which was a cross-sectional national health survey. The total study population amounted to 7,300 individuals (3,283 men, 4,617 women), aged 18 years and older. The prevalence of low HDL-C levels, as proposed by National Cholesterol Education Program Adult Treatment Panel III or International Diabetes Federation, was 23.8% in men and 47.5% in women. After adjusting for independent variables, there was a greater risk of low HDL-C with an increased body mass index, abdominal obesity, cigarette smoking, and decreased alcohol consumption. Physically inactive lifestyle in men and low fat intake in women were identified as factors associated with low HDL-C level. Conclusions The prevalence of low HDL-C levels is relatively high among Koreans, which may have important implications for public health. Identified associated factors should be considered for reducing the risk of low HDL-C levels in Koreans. (Circ J 2006; 70: 820 - 826)