In anticipation of U.S. forces deploying to Bosnia-Herzegovina, plans were established to conduct medical surveillance of all military service members. This surveillance would provide the Department of Defense with an overview of the hospitalization and outpatient morbidity experience of U.S. forces. Standardized collection of medical data from all U.S. camps using 14 diagnostic categories based on International Classification of Diseases, 9th Revision, codes began in March 1996. Special assessments for hantavirus and tick-borne encephalitis (TBE) infection risk were also conducted. The average disease and nonbattle injury rate for U.S. forces was 7.1 per 100 soldiers per week. Injuries accounted for 28% of medical visits, whereas undefined/other visits accounted for 33%. The majority of remaining visits were for respiratory (14%), dermatologic (10%), and gastrointestinal (6%) complaints. There was one confirmed and one suspected case of hemorrhagic fever with renal syndrome; only 0.1% of individuals (2 of 1,913) tested seroconverted to hantavirus during deployment. No cases of TBE were reported, and the overall low seroconversion rate (0.42%, 4 seroconversions among 959 unimmunized personnel) reflected a very low risk of infection with TBE-related viruses. Operation Joint Endeavor and follow-on Operations Joint Guard and Joint Forge have been extremely healthy deployments.