With guidelines similar to those recommended by the National Cholesterol Education Program (NCEP), 3,433 individuals were tested for blood cholesterol in a cholesterol screening and education project. The median age of the participants was 54 years. The mean blood cholesterol level for all races was 216 mg/dL (S.58 mmol/L) (men, 211 mg/dL [5.46 mmol/L], and women, 220 mg/dL [5.69 mmol/L]). In both sexes an increase in blood cholesterol levels was shown with age. Men reached peak cholesterol levels between 40 and 49 years old and women reached peak cholesterol levels between 50 and 59 years old. Classification of participants into desirable, borderline high, and high blood cholesterol based on the NCEP guidelines showed 44% of all participants had desirable, 32% had borderline high, and 24% had high blood cholesterol levels. The study also revealed that below age 40 years, 66% of all the participants had desirable, 26% had borderline, and only 9% had high (>240 mg/dL [>6.21 mmol/L]) cholesterol levels, whereas in those older than 40 years, only 27% had desirable, 37% had borderline high, and 35% had high blood cholesterol levels. The blood cholesterol distribution patterns presented in this article confirm earlier studies finding that age- and sex-related differences exist in blood cholesterol levels.