Background: Erectile dysfunction (ED) is the inability to achieve or maintain the adequate erection for intercourse. Heart failure is a major risk factor for erectile dysfunction. The aim of this study was to investigate the prevalence and factors associated with erectile dysfunction in systolic heart failure. Methods: In a cross-sectional study 100 male patients with systolic heart failure were selected using convenience sampling method. IIEF-5 questionnaire (the International Index of Erectile Function, 5-item version), MLHFQ (Minnesota Living with Heart Failure Questionnaire) and CES-D (Centre for Epidemiologic Studies Depression Scale) were used to obtain data. Results: Mean score of erectile dysfunction was 14.02 ± 6.26 and 80% of heart failure patient had erectile dysfunction. Erectile dysfunction was significantly associated with age (P < 0.001), education (P = 0.019), occupation (P = 0.002), hemoglobin level (P = 0.003), left ventricular ejection fraction (P = 0.030), cholesterol level (P = 0.001), renal dysfunction (P = 0.009), use of digoxin (P = 0.014), angiotensin converting enzyme inhibitors (P < 0.001), beta blocker (P = 0.001), diuretics (P = 0.035), depression (P < 0.001) and quality of life (P < 0.001). Conclusion: Erectile dysfunction (ED) was common in systolic heart failure and was associated with age, medical conditions, co morbidities, drugs for treatment and psychological disorders. In heart failure patients erectile dysfunction had negative impact on quality of life. Keywords: Heart Failure, Erectile Dysfunction, Depression, Quality of Life.