To evaluate the relation between low cholesterol level and mortality, the authors followed 482,472 Korean men aged 30-65 years from 1990 to 1996 after a baseline health examination. The mean cholesterol level of the men was 189.1 mg/100 ml at the baseline measurement. There were 7,894 deaths during the follow-up period. A low cholesterol level (<165 mg/100 ml) was associated with increased risk of total mortality, even after eliminating deaths that occurred in the first 5 years of follow-up. The risk of death from coronary heart disease increased significantly in men with the highest cholesterol level (> or =252 mg/100 ml). There were various relations between cholesterol level and cancer mortality by site. Mortality from liver and colon cancer was significantly associated with a very low cholesterol level (<135 mg/100 ml) without any evidence of a preclinical cholesterol-lowering effect. With lengthening follow-up, the significant relation between a very low cholesterol level (<135 mg/100 ml) and mortality from stomach and esophageal cancer disappeared. The cholesterol level related with the lowest mortality ranged from 211 to 251 mg/100 ml, which was higher than the mean cholesterol level of study subjects.