ABSTRACT: AIMS:Data on socioeconomic-related differences in heart failure (HF) care are sparse. Inequality in care may potentially contribute to a poor clinical outcome. We examined socioeconomic-related differences in quality of HF care among patients with incident HF with reduced ejection fraction (EF) (HFrEF). METHODS AND RESULTS:We conducted a nationwide population-based cohort study among patients with HFrEF (EF ?40%) registered from January 2008 to October 2015 in the Danish Heart Failure Registry, a nationwide registry of patients with a first-time primary HF diagnosis. Associations between individual-level socioeconomic factors (cohabitation status, education, and family income) and the quality of HF care defined by six guideline-recommended process performance measures [New York Heart Association (NYHA) classification, treatment with angiotensin-converting-enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB), beta-blockers and mineralocorticoid receptor antagonists, exercise training, and patient education] were assessed using multiple imputation and multivariable logistic regression controlling for potential confounders. Among 17 122 HFrEF patients included, 15 290 patients had data on all six process performance measures. Living alone was associated with lower odds of NYHA classification [adjusted OR (aOR) 0.81; 95% confidence interval (CI): 0.72-0.90], prescription of ACEI/ARB (aOR 0.76; 95% CI: 0.68-0.88) and beta-blockers (aOR 0.84; 95% CI: 0.76-0.93), referral to exercise training (aOR 0.75; 95% CI: 0.69-0.81), and patient education (aOR 0.73; 95% CI: 0.67-0.80). Compared with high-level education, low-level education was associated with lower odds of NYHA classification (aOR 0.93; 95% CI: 0.79-1.11), treatment with ACEI/ARB (aOR 0.99; 95% CI: 0.81-1.20) and beta-blockers (aOR 0.93; 95% CI: 0.79-1.09), referral to exercise training (aOR 0.73; 95% CI: 0.65-0.82), and patient education (aOR 0.86, 95% CI: 0.75-0.98). An income in the lowest tertile was associated with lower odds of NYHA classification (aOR 0.67; 95% CI: 0.58-0.79), prescription of ACEI/ARB (aOR 0.80, 95% CI: 0.67-0.95) and beta-blockers (aOR 0.88, 95% CI: 0.86-1.01), referral to exercise training (aOR 0.59, 95% CI: 0.53-0.64), and patient education (aOR 0.66; 95% CI: 0.59-0.74) compared with an income in the highest tertile. Overall, no systematic differences were seen when the analyses were stratified by sex and age groups. CONCLUSIONS:Living alone, low-level education, and income in the lowest tertile were associated with reduced use of recommended processes of HF care among Danish HFrEF patients with a first-time primary HF diagnosis. Efforts are warranted to ensure guideline-recommended HF care to all HFrEF patients, irrespective of socioeconomic background.