The influence of absorbed dietary cholesterol on plasma cholesterol concentration was studied in two populations, one Seventh Day Adventist (SDA) vegetarian and one nonvegetarian, representing a broad range of plasma cholesterol values and dietary cholesterol intakes. As a group, the SDA vegetarians had significantly lower levels of plasma cholesterol and triglycerides than did the nonvegetarians. This hypolipidemic pattern in the SDA vegetarians was apparently closely related to dietary habits, sinceanother group of SDA who were nonvegetarian had significantly higher plasma cholesterol and triglyceride levels than their vegetarian counterparts. Both the dietary intake of cholesterol and the percentage absorption of cholesterol were lower in vegetarians than in nonvegetarians. The mass of cholesterol absorbed increased linearly with the mass of cholesterol ingested in all groups, but no relationship could be demonstrated between absorbed cholesterol and plasma cholesterol concentration.