Disease nonbattle injury (DNBI) surveillance is a critical component of U.S. military force health protection and has been aggressively implemented by the U.S. Central Command. This study presents a multivariate analysis of factors associated with DNBI incidence rates as well as a description of morbidity measures associated with DNBI from U.S. Navy ships deployed to the Middle East from October 2000 through September 2001. Weekly DNBI reports (N = 331) from a total of 44 individual units representing six different classes of U.S. Navy ships were included in the analysis. There were statistically significant differences in summary and categorical DNBI rates associated with ship class, season, and presence of female sailors embarked. The top three DNBI categories associated with the most lost workdays because of sick in quarters and hospitalization were other medical/surgical (36%), infectious gastrointestinal (23%), and all types of nonbattle injury combined (17%).