Objective The mortality rate from cardiovascular disease(CVD) among young adults has declined less than that in the older population, raising concerns about the increasing prevalence of obesity-related conditions including hypercholesterolemia in the younger population. We investigated the levels of total cholesterol(TC) and low-density lipoprotein cholesterol(LDL-C) and prevalence, awareness, treatment and control rates of hypercholesterolemia based on age. Methods Nationally representative samples of 19525 subjects aged ≥20 years were analyzed from the Korea National Health and Nutrition Examination Surveys 2008-2010. Anthropometric and clinical data and lipid profiles were examined, and rates of prevalence, awareness, treatment and control of hypercholesterolemia were assessed. Results Age-standardized mean levels of TC, high-density lipoprotein cholesterol, LDL-C and triglycerides were 186.8, 48.0, 112.9, and 136.0 mg/dL, respectively. Age-standardized prevalence of high TC (≥ 240 mg/dL) and LDL-C (≥ 160 mg/dL) were 9.9% (12.1%) and 4.4% (5.5%) in men (women), respectively. Among subjects with high TC, awareness and treatment rates were significantly lower in younger adults compared to older adults (awareness, 14.2% vs. 45.1% in men, 24.2% vs. 44.9% in women; treatment, 7.9% vs. 39.7% in men, 21.1% vs. 42.1% in women), indicating significant discrepancies in awareness and treatment rates of hypercholesterolemia between younger and older adults. Conclusion Compared to the elderly, significant proportions of young and middle-aged adults are unaware of their hypercholesterolemia and are not treated with proper lipid-lowering medications. Early screening, education and proper management should be stressed in national public healthcare policies in order to reduce the increasing burden of CVD in the younger population with undiagnosed hypercholesterolemia.