Our goals in this proposed study are to estimate the US nationwide prevalence and incidence of interstitial cystitis (IC) using a large, heterogeneous cohort from the Veterans Affairs healthcare system, the largest integrated health care system in the US. We will also prospectively enroll subjects to identify the impact of IC on individual health and test the value of a specific set of urine biomarkers already identified by our research team to diagnose IC. This study will dramatically enhance our understanding of the epidemiology of IC and will be the basis for multiple prospective studies aiming to increase diagnostic accuracy, and thus has direct relevance to human health and patient care.