Young, healthy individuals living in Sri Lanka often consume a diet containing coconut oil as their main source of fat. Blood lipid values and selected platelet related factors have been measured in a group of 16 free living young adults, ages 16 to 21, before and 8 weeks after they had been shifted from their usual diet to a similar one in which the coconut oil was replaced by whole milk powder and corn oil. The results indicate that their blood cholesterol, cholesteryl ester, and several other related circulating blood lipid values, as well as the platelet factor 4 values, were elevated prior to the diet change. Many of these factors, associated as risk factors for atherogenesis, were substantially reduced at the end of the diet change. The only plasma components which were altered substantially were the triglycerides and the HDL cholesterol. These results suggest that the special atherogenic effects of coconut oil that have been demonstrated in so many animal models may be similarly active in humans