More than 1,000 licensed naturopathic physicians practice in the United States, and iridology is being described as "the most valuable diagnostic tool of the naturopath." Some therapists are using iridology as a basis for recommending dietary supplements and/or herbs. Several US iridologist organizations exist: the National Iridology Research Association is an iridologists' service organization, the International Association of Iridologists is the leading organization for European-style iridology and runs training programs (minimum of 72 hours in class), and the Bastyr Naturopathic College in Seattle, Wash, has an elective course on iridology (J. Colton, e-mail communication, December 2, 1998). In the United States, insurance programs do not normally cover iridology, but in some European countries, they do. In Germany, for instance, 80% of the Heilpraktiker (nonmedically qualified health practitioners) practice iridology. Ophthalmologists may therefore ask what is iridology and how valuable is it?