The Stockholm Prospective Study--in a 14.5 year follow-up of 3486 men--found plasma triglycerides but not plasma cholesterol to be an independent risk factor for ischaemic heart disease. This finding stands in sharp contrast to the opposite results of the 8.5 year follow-up of the Western Collaborative Group Study. Differences between the two studies are discussed as one way of explaining the varying results--the most important probably being the use of different end-points for the diagnosis of ischaemic heart disease, but geographical, environmental and ethnic differences may also be of importance.