Similarities and differences in hospitalization rates among five racial groups serving in the Navy during a 3-year period (1973-75) were examined, and the differences in terms of sociological and occupational factors were evaluated. Overall annual hospitalization rates per 10,000 men were blacks, 1,413; whites, 1,109; American Indians, 923; Asian-Americans, 683; and Malaysians (Filipinos), 508.Explanations for the low Malaysian hospitalization rate included selection of the fittest for service, age and job experience, and a low percentage of assignments to physically arduous occupations. Although blacks had the highest rates for many medical conditions, their rates for injuries, respiratory diseases, and infective disorders were comparable with those for whites. Blacks had the highest rates for several non-life-threatening conditions that required surgical procedures; this finding suggested that the Navy Medical Department had filled a longstanding need for corrective treatment.Although the results of this study should be useful to military medical planners responsible for the health care of all naval personnel, the authors conclude that detailed longitudinal studies are needed to establish more clearly the underlying biological and sociological factors associated with racial differences in morbidity.