Background. Guillain-Barré Syndrome (GBS), the leading cause of acute flaccid paralysis worldwide, is an autoimmune disorder involving the loss of the myelin sheaths encasing peripheral nerve axons, leading to a loss of nerve signaling and typically ascending paralysis. A number of infectious triggers have been identified, with Campylobacter being most common. Limited data are available regarding GBS in U.S. service members at a high risk of exposure to numerous GBS-associated infectious agents. Findings. Medical encounter data were obtained from the Armed Forces Health Surveillance Center (Silver Spring, MD). Active duty personnel with an incident GBS diagnosis were matched by age, sex, and time with up to 4 controls. Demographic, antecedent infectious gastroenteritis (IGE), and deployment covariates were used to explore GBS risk in this population. The overall incidence was 2.28/100,000 persons (95% confidence interval: 2.03-2.54) with 19.1% (60/314) receiving GBS-related medical care for more than one year. The majority of cases were male, Caucasian and under 25 years of age. There was an increased risk of GBS three months following a documented episode of IGE (Odds Ratio: 5.33; p = 0.03). We also found an association with service in the Air Force and Navy (compared to Army personnel) with odds ratios of 1.39 (p = 0.05) and 1.44 (p = 0.02), respectively. Conclusion. GBS incidence in the U.S. military is slightly higher than the general population and is associated with an antecedent IGE. Future studies are warranted to assess whether there are GBS-associated infectious or environmental exposures inherent to military populations.