Parry-Romberg syndrome (PRS) is a rare neurocutaneous disorder characterized by progressive facial hemiatrophy. In this study, 205 patients with PRS were surveyed using the Internet. Estimates of the frequency of limb involvement (19%), epilepsy (11%), and other clinical and etiologic features were obtained. There was a wide range of age at onset and considerable diagnostic overlap with scleroderma "en coup de sabre."