Atherosclerosis appears already in the first years of life. Several factors may accelerate the age of onset and the gravity of its symptoms. Particular importance is attributed to lipid metabolism in youth. Ther Authors studied the rates of cholesterol, HDL, LDL, triglycerides, apolipoproteins AI and B100, lipoprotein a and several anamnestic and anthropometric parameters in a group of 103 young people of Rome, between 16 and 19 years of age. They processed these data statistically and compared them with those of a similar American group. The results showed a tendency to fatness in the Italian sample, and to dyslipidosis in the American group. Besides, the subjects who had been breast-fed presented higher blood levels of cholesterol and apolipoprotein B100.