The recent progress made in understanding the normal biology and biochemistry of the extracellular matrix of human skin has allowed us to identify several different levels at which errors could be introduced into the structure and metabolism of collagen or elastin, the two major fibrillar components of the dermis. Currently, several heritable cutaneous diseases are known to display distinct collagen or elastin abnormalities. This article reviews some of the heritable cutaneous diseases and highlights those entities in which definite information on molecular alterations in collagen or elastin is available.