To determine regional estimates of pathogen-specific prevalence and incidence, as well as, describe morbidity associated with diarrhea among deployed US military and similar populations, a systematic review was conducted for publications between January 1990 to June 2005. Point estimates and confidence intervals of pathogen prevalence and travelers' diarrhea incidence were combined in a random effects model and assessed for heterogeneity. In total, 262 studies were identified for potential inclusion, of which 52 fulfilled inclusion criteria. Overall, 38% were from the Middle East, 29% from Southeast Asia, 27% from Latin America/Caribbean, and 6% from sub-Saharan Africa. Median duration of travel was 1.5 months (interquartile range, 1-3 months). Enterotoxigenic Escherichia coli (ETEC), Campylobacter, and Shigella were identified as causing 38-45% of diarrhea, with regional and population differences. Incidence based on self-report was higher than studies using passive surveillance or clinic-based methods (29 versus 7 versus 6 episodes per 100 person-months, respectively) without regional differences.