The skin on the fingertips and palmar and plantar surfaces of man is not smooth. It is grooved by curious ridges, which form a variety of configurations. These ridge configurations have attracted the at­ tention of laymen for millenia. They have also evoked the serious interest of scientists for more than three centuries. The anatomist Bidloo provided a description of ridge detail in the seventeenth cen­ tury. Since then, additional information has been added by anthro­ pologists, biologists, and geneticists. For the last century, the fact that each individual's ridge configurations are unique has been uti­ lized as a means of personal identification especially by law enforce­ ment officials. Widespread medical interest in epidermal ridges de­ veloped only in the last several decades when it became apparent that many patients with chromosomal aberrations had unusual ridge formations. Inspection of skin ridges, therefore, promised to provide a simple, inexpensive means for determining whether a given patient had a particular chromosomal defect. However, the promise was only partially fulfilled because of the inherent variability of skin ridge configurations. It was possible to draw conclusions about ridge ab­ normalities in groups of patients but not always in a given individual. Patients and clinicians became somewhat disenchanted with the clinical value of studying ridges.