Gastrointestinal (GI) infections in the U.S. Armed Forces have consistently been among the most frequent disease and non-battle injury diagnoses. A retrospective analysis of surveillance data categorized as GI infections among active component service members during 2012-2014 was performed. During the study period, 99% of inpatient and outpatient GI encounters were reported as nonspecific GI infection (13,331 cases per 100,000 people), leaving only a small percentage of cases attributed to specific causes. The five most common organisms associated with GI infections were Campylobacter (10.30 per 100,000 people), nontyphoidal Salmonella (7.43), Giardia (3.15), Shigella (2.11), and norovirus (1.25). The civilian population incidence rates of foodborne diseases during the same time period are significantly greater than incidence rates within the U.S. active component for all select bacterial and parasitic pathogens, except Campylobacter. Nonspecific gastroenteritis incidence increased during winter months, which is similar to the seasonal pattern for viruses such as norovirus. The preponderance of nonspecific infections highlights the need for increased testing and a more in-depth review of the impact of GI infections on operational effectiveness within the U.S.