Abstract: INTRODUCTION: Serious Mental Illness (SMI) adds complexity to end of life care including medical decision making. For complex patients, enrollment in team-based hospice care providescoordinated services and supports. This retrospective study evaluated if the combinations of mental health care or palliative care increased hospice enrollment in the last 6 months of life. METHODS: We identified deceased Veterans with diagnoses of heart failure (HF) and SMI. SMI was defined as schizophrenia spectrum or bipolar spectrum disorder. We categorized the SMI population into 4 groups: those with mental health and palliative care (n = 2973), only mental health (n = 4333), only palliative care (n = 892), or neither (n = 1171). The outcome of hospice use in the 6-months before death was measured with VA and Medicare records. Logistic regression compared the mental health and palliative care groups to the reference group and included adjustment for demographics and comorbidities. RESULTS: The cohort included 9369 Veterans with HF and SMI who died between 2011 and 2020. Relative to the reference group (23.9 % hospice), those with mental health engagement had lower odds of receiving hospice (adjusted Odds Ratio (aOR) = 0.74; 95 % confidence interval (CI) 0.62,0.87). Exposure to palliative care increased the adjusted odds of hospice in those with mental health services (aOR = 6.67, 95 % CI 5.61, 7.92) and with only palliative care (aOR = 5.96, 95 % CI 4.86, 7.32). CONCLUSION: This study demonstrates a gap in hospice enrollment for people with SMI. Palliative care improves the gap. Increased collaboration between mental health and palliative providers and cross-training may improve the experience of people with SMI.