Epidemiological, laboratory and experimental studies make it clear that dietary cholesterol (DC) and saturated fat, independently and together, are hypercholesterolaemic and atherogenic. Some work suggests that DC, usually given as egg yolk, is the more important, but often they are consumed together. There is a threshold, usually between 100 and 200 mg/day, below which small increments do not affect plasma cholesterol (PC) and another, usually between 500 and 600 mg/day, above which there is little additional change. However, there is considerable individual variation. Recent work suggests that regression of atherosclerosis can occur in the human as in the non-human primate. An alternative, phased, preventive diet has been designed which is nutritionally adequate, ecologically sound, and economical. It also has an historical basis.