PURPOSE: The RAND Interstitial Cystitis Epidemiology survey estimated that 2.7% to 6.5% of United States women have urinary symptoms consistent with a diagnosis of interstitial cystitis/bladder pain syndrome. We describe the demographic and clinical characteristics of the symptomatic community based RAND Interstitial Cystitis Epidemiology cohort, and compare them with those of a clinically based interstitial cystitis/bladder pain syndrome cohort. MATERIALS AND METHODS: Subjects included 3,397 community women who met the criteria for the RAND Interstitial Cystitis Epidemiology high sensitivity case definition, and 277 women with an interstitial cystitis/bladder pain syndrome diagnosis recruited from specialist practices across the United States (clinical cohort). Questions focused on demographic information, symptom severity, quality of life indicators, concomitant diagnoses and treatment. RESULTS: Average symptom duration for both groups was approximately 14 years. Women in the clinical cohort reported worse baseline pain and maximum pain, although the absolute differences were small. Mean Interstitial Cystitis Symptom Index scores were approximately 11 for both groups, but mean Interstitial Cystitis Problem Index scores were 9.9 and 13.2 for the clinical cohort and the RAND Interstitial Cystitis Epidemiology cohort, respectively (p