BACKGROUND Phosphodiesterase-5 inhibitor (PDE5i) treatment for erectile dysfunction is associated with lower mortality compared with no treatment for erectile dysfunction after myocardial infarction (MI). There are conflicting results regarding the impact of PDE5i treatment on mortality in conjunction with nitrate medication. OBJECTIVES The purpose of this study was to investigate the association between PDE5i treatment and cardiovascular outcomes in men with stable coronary artery disease treated with nitrate medication. METHODS Using the Swedish Patient Register and the Prescribed Drug Register we included men with previous MI or revascularization in 2006-2013 who had 2 dispensed nitrate prescriptions within 6 months. Exposure was defined as at least 2 filled prescriptions of any PDE5i. We performed multivariable Cox proportional hazard regression to estimate HRs with 95% CIs for all -cause, cardiovascular, and noncardiovascular mortality, MI, heart failure, cardiac revascularization, and major cardiovascular events (MACE). RESULTS In total, 55,777 men were treated with nitrates and 5,710 men with nitrates and a PDE5i. The combined use of PDE5i treatment with nitrates was associated with higher mortality (HR: 1.39; 95% CI: 1.28-1.51), cardiovascular mortality (HR: 1.34; 95% CI: 1.11-1.62), noncardiovascular mortality (HR: 1.40; 95% CI: 1.27-1.54), MI (HR: 1.72; 95% CI: 1.55-1.90), heart failure (HR: 1.67; 95% CI: 1.48-1.90), cardiac revascularization (HR: 1.95; 95% CI: 1.78-2.13), and MACE (HR: 1.70; 95% CI: 1.58-1.83). CONCLUSIONS The use of a PDE5i in combination with nitrate medication in men with stable coronary artery disease may pose an increased hazard for cardiovascular morbidity and mortality. Careful patient -centered consideration before prescribing PDE5is to patients with cardiovascular disease using nitrate medication is warranted. (J Am Coll Cardiol 2024;83:417-426) (c) 2024 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the CC BY -NC -ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).