Background: The risk of active TB resulting from military deployment to endemic areas is unknown. It has typically been assumed that the risk of TB approximates the risk among local nationals in that country. Purpose: This nested casecontrol study assesses the putative association of overseas deployment with active tuberculosis among active-component U.S. military service members. Methods: Deployment histories and other exposures among 578 active TB cases and 2312 controls matched on year of entry into service and length of service between 1990 and 2006 were compared in 2009 using multivariate conditional logistic regression. Multiple imputation methods were used to account for missing data. Results: The matched OR of active TB for military deployers as compared to nondeployers was 1.18 (95% CI=0.91, 1.52). A significant association of deployments of 90179 days was found, but this was inconsistent with the overall negative result. Significant associations were seen with foreign birth and nonwhite racial or ethnic groups. Overseas stationing in Korea was also found to be associated with active TB. Conclusions: No strong or consistent association was found between active TB and deployment, but an association was seen with long-term residence in TB-endemic countries (Korea). The strongest risk factors for active TB in the U.S. military population were found to exist prior to accession into military service. These conclusions were robust in sensitivity analysis.