Although there are at present in the neighborhood of two hundred reported cases of arachnodactyly, the syndrome is little known to the members of the American medical profession. Most of the literature is in French or German, and in this country few but ophthalmologists are familiar with the condition. Since arachnodactyly should interest orthopedists, pediatricians and physicians in general, as well as ophthalmologists, we wish to summarize its characteristics and report two cases with particular reference to the medical complications. Described first, in 1896, by Marfan1 as "pattes d'araignée" or "dolichosténomélie," the condition acquired the more familiar name arachnodactyly (spider fingers) from Achard2 in 1902. The first case recognized in America was described by Piper and Irvine-Jones,3 in 1926. Comprehensive articles on arachnodactyly have been published by Young,4 Ormond,5 Weve,6 and Burch.7 The syndrome is familial and congenital, with the following major characteristics: Abnormally long gracile