Epidemiologic data on 176 patients with acute Guillain-Barré syndrome observed over a nine-year period in the New York-New Jersey metropolitan area are presented. A striking predilection for patients aged 16 to 25 years, with a second lesser peak between ages 45 to 60, was found. Seasonal clustering of patients occurred, with nearly half the patients afflicted during the four-month period of late summer and fall. The distribution between men and women was equal. In this series 23% of the patients required tracheostomy, and 5% had a fatal course.