The lack of a precise working definition of interstitial cystitis may have resulted in the de facto use of the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK) "research" definition by clinicians. We evaluated these strict criteria in light of the broader inclusion criteria for patients evaluated in the Interstitial Cystitis Database study to determine their utility in clinical practice as a useful basis for the diagnosis of interstitial cystitis.