As bladder pain syndrome/interstitial cystitis (BPS/IC) has been demonstrated to proceed through the inflammatory pathways to cause endothelial dysfunction, and endothelial dysfunction is a major factor in the development of ED, it is possible that BPS/IC may be associated with ED. This study set out to investigate the putative association between ED and BPS/IC by using a population-based data set and case-control design in Taiwan. We obtained the data from Taiwan's National Health Insurance Research Database. Cases included 32,856 ED patients ≥ 18-years old and 164,280 matched controls. Conditional logistic regression analyses were performed to compare the odds ratios (OR) and corresponding 95% confidence intervals (CIs) of having been previously diagnosed with BPS/IC in cases and controls. Among the total sample of 197,136 subjects, the prevalence of prior BPS/IC was 0.05%. The prevalence of prior BPS/IC was 0.10% and 0.04% for cases and controls, respectively (P<0.001). Conditional logistic regression analysis revealed that when compared with controls, the OR of prior BPS/IC for cases was 1.75 (95% CI=1.12-2.71) after adjusting for monthly income, geographic location, hypertension, diabetes, coronary heart disease, hyperlipidemia, renal disease, obesity, depressive disorder, alcohol abuse/alcohol-dependence syndromes and the number of outpatient visits within 1 year before index date. Subjects aged between 18 and 39 were additionally found to have the highest ORs for prior BPS/IC among cases when compared with controls (OR=10.40; 95% CI=2.93-36.94). There was an association between BPS/IC and ED. The youngest cases with ED were found to have the strongest magnitudes of association with BPS/IC.