Using Andersen's (1995) [Andersen RM. Revisiting the behavioral model and access to medical care: does it matter? Journal of Health and Social Behavior 1995;36:1-10] behavioral model of healthcare use as our theoretical framework, we examined predisposing (i.e., sociodemographic), enabling (i.e., access resources), and need (i.e., illness) models of outpatient medical and mental healthcare utilization among a national sample of US veterans. Participants were 20,048 nationally representative participants completing the 2001 National Survey of Veterans. Outcomes were healthcare use variables for the past year, including the number of Veterans Affairs (VA) and non-VA outpatient healthcare visits, and whether VA and non-VA mental health treatment was used. Univariate results demonstrated that numerous predisposing, enabling and need variables predicted both VA and non-VA healthcare use intensity and mental healthcare use. In multivariate analyses, predisposing, enabling and need variables demonstrated significant associations with both types of healthcare use, but accounted for more variance in mental healthcare use. Need variables provided an additive effect over predisposing and enabling variables in accounting for medical and mental healthcare use, and accounted for some of the strongest effects. The results demonstrate that need remains an important factor that drives healthcare use among veterans and does not seem to be overshadowed by socioeconomic factors that may create unfair disparities in treatment access.