This study was performed to evaluate the prevalence of erectile dysfunction (ED) and to explore its correlation to chronic prostatitis in China. A cross-sectional investigation from a large cohort study of Chinese men was used in this survey. A questionnaire consisting of general information regarding socio-demographics, chronic disease history, sexual function, the National Institutes of Health-Chronic Prostatitis Symptom Index, and the International Index of Erectile Function-5 (IIEF-5) was administered to 15 000 Chinese men aged from 15 to 60. The prevalence of ED was determined from the patient's self-evaluation and IIEF-5 score. The eligible individual both was married and had intercourse experience. In total, there were 12 743 respondents, giving a response rate of 84.95%. Among 7372 eligible men, ED prevalence as assessed by self-report and IIEF-5 score was 12.0% and 17.1%, respectively. Among 771 men with prostatitis-like symptoms, ED prevalence as assessed by self-report and IIEF-5 score was 39.3% and 30.1%, respectively. Among 370 men suffering from chronic prostatitis, ED prevalence as assessed by self-report and IIEF-5 score was 40.5% and 35.1%, respectively. The prevalence of self-reported and IIEF-5 score-assessed ED had high correlation with increasing age among all eligible men, men with prostatitis-like symptoms, and men with chronic prostatitis (P(t) < .05, P(s) < .05, P(cp) < .05). ED prevalence as assessed by both self-report and IIEF-5 score was higher in men with prostatitis-like symptoms and with chronic prostatitis than in the general group (P(s) < .05, P(cp) < .05). The prevalence of ED was higher in the prostatitis population than in the general population with either self-reported or IIEF-5 score assessment. The prevalence was higher with self-reported than with IIEF-5 assessment in men with prostatitis. Estimates of ED prevalence among men with prostatitis should not rely on self-reporting alone in that this is likely to overestimate the true prevalence.