Background. Homelessness is associated with high rates of hospitalizations and age-adjusted mortality. Few studies have examined whether homeless people are admitted to the hospital at an earlier age than the general population or for different diagnoses. Methods. We compared the age at admission and the primary discharge diagnoses in a national sample of 43,868 hospitalized veterans. Results. The difference in median age between homeless and housed inpatients ranged from 10–18 years for medical-surgical diagnoses and 3–4 years for psychiatric and substance abuse diagnoses (p#.005 for all diagnoses). Homeless veterans were more likely to have been admitted for psychiatric and substance abuse diagnoses (79.9%), compared with housed veterans (29.1%). Conclusions. Substance abuse and psychiatric illness account for the majority of admissions among homeless veterans. Among all diagnostic groups, homeless people were admitted at younger ages. Our findings suggest that homeless people have either a more rapid disease course, leading to earlier morbidity, or lower admission threshholds sufficient to generate hospital admission.