Objective <p>To assess ethnic disparities in 90-day outcomes among patients hospitalized with acute decompensated heart failure (ADHF), and in the use of guideline-directed medical therapy (GDMT) among those with heart failure with reduced ejection fraction (HFrEF).</p> Methods <p>This retrospective cohort study included patients hospitalized with ADHF at a medium-sized health system between January 2018 and May 2024. Primary outcomes were 90-day mortality and readmission. Among patients with HFrEF, GDMT use was assessed as a secondary outcome. Multilevel logistic regression was used to evaluate associations between ethnicity and outcomes.</p> Results <p>A total of 14,644 patients with ADHF were included. No significant differences were observed in 90-day mortality (OR 0.69, 95% CI 0.21–2.24, <i>P</i> = 0.540) or 90-day readmission (OR 0.78, 95% CI 0.51–1.19, <i>P</i> = 0.267) between Hispanic and non-Hispanic patients. Among HFrEF patients, Hispanic patients had higher odds of receiving beta blockers (OR 1.32, 95% CI 1.04–1.68, <i>p</i> = 0.023), mineralocorticoid receptor antagonists (OR 1.37, 95% CI 1.05–1.79, <i>p</i> = 0.021), and renin-angiotensin system blockers (OR 1.51, 95% CI 1.17–1.95, <i>p</i> = 0.002). In contrast, no significant difference was observed in the use of sodium-glucose cotransporter-2 inhibitors between the two groups (OR 1.67, 95% CI 0.69–4.05, <i>p</i> = 0.254). Additionally, patients with Medicare (OR 0.65, 95% CI 0.57–0.74, <i>p</i> &lt; 0.001) or unspecified insurance (OR 0.18, 95% CI 0.11–0.28, <i>p</i> &lt; 0.001) had lower odds of receiving GDMT compared to self-pay patients.</p> Conclusion <p>This study reveals a counterintuitive pattern of higher GDMT use among Hispanic HFrEF patients, underscoring the need to leverage community-based resources and patient assistance programs to address disparities. Further prospective studies are needed to confirm these findings or policy changes to reduce insurance-related barriers to GDMT.</p>