Arteriosclerosis, is a disease of the arteries. It is often called "hardening of the arteries" because it involves hardening, thickening, and loss of elasticity in the artery walls. There are several forms of arteriosclerosis. Two types are Monckeberg's arteriosclerosis, in which the middle layer of the arteries becomes stiffened by calcium deposits, and arteriolar sclerosis, which affects the body's smaller arteries. But by far the most widespread form of arteriosclerosis is the type called atherosclerosis. Atherosclerosis affects medium and large arteries, especially those that carry blood to the heart, brain, kidneys, and legs. The effects of the disease appear mainly in middle-aged or older people, but they may also strike young people. Atherosclerosis ranks as a major health problem in the United States and other developed countries. The remainder of this article discusses atherosclerosis.