Tobacco use is of particular concern to the U.S. Department of Defense because the military historically has had higher and heavier rates of tobacco use than civilians. Few prospective studies have examined the association of cigarette smoking with medical outcomes, particularly among initially healthy female military personnel. This prospective cohort study followed over 5,000 young U.S. Navy female recruits varying in their smoking status at entry into the Navy and collected their subsequent hospitalization data (i.e., International Classification of Diseases, Ninth Revision codes) for up to 7-8 years of service. Results indicated that after adjusting for differences in time at risk and sociodemographic variables, daily smokers (compared with never-and other smokers) had higher rates of hospitalization for any reason and for musculoskeletal conditions. Daily smokers also had higher rates than never- and other smokers for non-pregnancy-related hospitalizations and for mental disorders, although only the daily/other differences reached statistical significance. Daily smokers' average number of days hospitalized was significantly longer than that of never- and other smokers. Results suggest that young women do not have to wait decades to experience the harmful effects of smoking. A recent history of cigarette smoking is an important determinant of hospitalization risk for even young healthy women in the U.S. Navy.