OBJECTIVES: The National Institutes of Diabetes and Digestive and Kidney Diseases (NIDDK) requires cystoscopic features of interstitial cystitis (IC) as a diagnostic criterion, yet this excludes significant numbers of patients with clinical symptoms of IC/Painful Bladder Syndrome (PBS).  Patient-reported, symptom-based measures may be more appropriate for identifying IC/PBS patients.  Existing measures have poor specificity, likely due to inadequate content validity.  The objective was to conduct qualitative interviews with patients to identify key IC symptoms, and the language used to describe them, to develop a new symptom-based IC screener.  METHODS: A total of 44 IC/PBS patients with a confirmed diagnosis in the US, France and Germany (aged 22-72) were interviewed about their symptoms and subsequent impact on quality of life.  Ten US overactive bladder (OAB) patients (aged 31-69), a condition often confused with IC, were also interviewed to improve specificity.  Interviews included open-ended questions, creative tasks and focussed discussion.  Thematic analysis was conducted utilising grounded theory methods. RESULTS: Key symptoms identified by IC/PBS patients were the urge to urinate, urination frequency, and pain.  Urge had four components: 1) need to urinate driven by pain; 2) a need to urinate to avoid pain getting worse; 3) a constant need to urinate and; 4) a sudden need to urinate.  In contrast, OAB patients reported urge that did not involve pain.  Both OAB and IC/PBS patients experienced high day and night-time urination frequency.  IC pain was perceived to be in the bladder, abdomen or pelvis, and was most commonly described as “pressure”, “burning”, “sharp” and “discomfort”.  The screener items were developed using these data, with guidance from IC experts.  CONCLUSIONS: Utilising an extensive, geographically diverse interview process, we elicited key symptoms that differentiate IC/PBS from OAB patients. Efforts to optimize the sensitivity and specificity of the new screener are critical to accurately identify patients with IC/PBS.