The coronary arterial intima undergoes a sequence of changes following injury, before the appearance of lipids. Studies of the evolution of coronary arterial pathology in the transplanted human heart defines a pattern which is the stereotype of the artery's response to insult. The first stage is that of intimal hyperplasia and disruption of the internal elastic lamina; the second the migration into the thickened intima of medial smooth muscle cells; the third the incursion of lipids. The end result is atheroma, indistinguishable morphologically from that which is found in the usual setting. The same sequence of arterial events can be sought, and found, in the general population (at least in coronary-prone societies), the first being identifiable commonly in infancy and childhood. These changes, reported in the literature over many years, have been generally assumed to be benign accompaniments of growth and development. They are likely to be the precursors of atherosclerosis and the seat of later lipid deposition, without which that deposition would not occur. The cause(s) of coronary arterial disease are therefore concerned more with these pre-lipid stages than with the lipids themselves, which are complicating rather than causative factors.