Bladder pain syndrome / interstitial cystitis (BPS/IC) is a chronic, multifactorial and relapsing condition. Aetiology includes: inflammation, allergic, neuropathic, auto immune, vascular factors, etc. This study from Taiwan aimed to investigate the risk of coronary heart disease (CHD) among IC cases during a three-year follow-up period, compared with non-IC patients over the same period. This appears to be first large scale population-based study of 4512 subjects. It was found that subjects with IC have around a 2.5 times higher incidence of CHD at one, two and three year follow-up. Endothelial dysfunction may be a common pathogenic factor between IC and CHD.