Background: The health concerns that spur care-seeking in emergency departments (EDs) among homeless populations are not well described. The Veterans Affairs (VA) comprehensive healthcare system does not require health insurance and thus offers a unique window into ED service use by homeless veterans. Objective: This study examined the top 10 diagnostic categories for ED use among homeless and non-homeless veterans classified by age, gender, and race/ethnicity. Design: An observational study was conducted using national VA administrative data from 2016 to 2019. Participants: Data on 260,783 homeless veterans and 2,295,704 non-homeless veterans were analyzed. Main measures: Homelessness was defined as a documented diagnostic code or use of any VA homeless program. Presenting diagnoses to the ED were grouped based on Clinical Classifications Software Refined (CCSR) categories endorsed by the Agency for Healthcare Research and Quality (AHRQ). Key results: The most common diagnostic categories for ED use among homeless veterans were, in order, musculoskeletal pain, alcohol-related disorders, suicidal behaviors, low back pain, and non-specified conditions, which together accounted for 22–24% of all ED visits. Among non-homeless veterans, alcohol-related disorders, suicidal behaviors, and depressive disorders did not number in the top 10 diagnostic categories for ED use. Some differences between homeless and non-homeless veterans presenting for ED care, such as age, gender, and race/ethnicity largely mirrored known epidemiological differences between these groups in general. But respiratory infections and symptoms were only in the top 10 for black veterans and depressive disorder was only in the top 10 for Hispanic veterans. Conclusions: These data suggest that addressing psychosocial factors and optimizing healthcare for behavioral health and pain conditions among veterans experiencing homelessness has the potential to reduce emergency care-seeking.