Aims To determine tolerability and the optimal dose regimen of the soluble guanylate cyclase stimulator vericiguat in patients with chronic heart failure and preserved ejection fraction (HFpEF). Methods and results SOCRATES-PRESERVED was a prospective, randomized, placebo-controlled double-blind, Phase 2b dose-finding study in patients with HFpEF (ejection fraction >= 45%). Patients received vericiguat once daily at 1.25 or 2.5 mg fixed doses or 5 or 10mg titrated from a 2.5 mg starting dose, or placebo for 12 weeks. The two primary endpoints were change from baseline in log-transformed N-terminal pro-B-type natriuretic peptide (NT-ProBNP) and left atrial volume (LAV) at 12 weeks. Patients (N = 477; 48% women; mean age 73 +/- 10 years; baseline atrial fibrillation 40%) were randomized within 4 weeks of HF hospitalization (75%) or outpatient treatment with intravenous diuretics for HF (25%) to vericiguat (n = 384) or placebo (n = 93). In the pooled three highest dose arms change in logNT-proBNP (vericiguat: +0.038 +/- 0.782 log(pg/mL), n = 195; placebo: -0.098 +/- 0.778 log(pg/mL), n = 73; one-sided P = 0.8991, two-sided P = 0.2017), and change in LAV [vericiguat: -1.7 +/- 12.8 mL (n = 194); placebo: -3.4 +/- 12.7 mL (n = 67), one-sided P = 0.8156, two-sided P = 0.3688] were not different from placebo. Vericiguat was well tolerated (adverse events: vericiguat 10 mg arm, 69.8%; placebo, 73.1%), with low discontinuation rates in all groups, and no changes in blood pressure at 10 mg compared with placebo. The pre-specified exploratory end-point of Kansas City Cardiomyopathy Questionnaire Clinical Summary Score improved in the vericiguat 10 mg arm by mean 19.3 +/- 16.3 points [median 19.8 (interquartile range 10.4-30.7)] from baseline (mean difference from placebo 9.2 points). Conclusion Vericiguat was well tolerated, did not change NT-proBNP and LAV at 12 weeks compared with placebo but was associated with improvements in quality of life in patients with HFpEF. Given the encouraging results on quality of life, the effects of vericiguat in patients with HFpEF warrant further study, possibly with higher doses, longer follow-up and additional endpoints.