Abstract: This invention is a method for measuring the ability of a human to absorb cholesterol. The method uses two different cholesterol tracers, the first injected into the blood stream and the second ingested by the human subject. After a waiting period a blood sample is taken from the human subject and analyzed to determine percent cholesterol absorption based on the actual amounts of the two naturally occurring, metabolically stable cholesterol tracers in the blood. The method of this invention is useful in identifying human subjects as high cholesterol absorbers and thereafter administering therapeutic agents to the subject that inhibit the absorption of cholesterol.