Background Heart failure (HF) is a global challenge, with lower- and middle-income countries (LMICs) carrying a large share of the burden. Treatment for HF with reduced ejection fraction (HFrEF) improves survival but is often underused. Economic factors might have an important effect on the use of medicines. Methods and results This analysis assessed prescription rates and doses of renin-angiotensin system (RAS) inhibitors, beta-blockers, and mineralocorticoid receptor antagonists at discharge and 6-month follow-up in 8669 patients with HFrEF (1458 from low-, 3363 from middle-, and 3848 from high-income countries) hospitalized for acute HF in 44 countries in the prospective REPORT-HF study. We investigated determinants of guideline-recommended treatments and their association with 1-year mortality, correcting for treatment indication bias. Only 37% of patients at discharge and 34% of survivors at 6 months were on all three medication classes, with lower proportions in LMICs than high-income countries (19 vs. 41% at discharge and 15 vs. 37% at 6 months). Women and patients without health insurance, or from LMICs, or without a scheduled medical follow-up within 6 months of discharge were least likely to be on guideline-recommended medical therapy at target doses, independent of confounders. Being on >= 50% of guideline-recommended doses of RAS inhibitors, and beta-blockers were independently associated with better 1-year survival, regardless of country income level. Conclusion Patients with HFrEF in LMICs are less likely to receive guideline-recommended drugs at target doses. Improved access to medications and medical care could reduce international disparities in outcome.