Introduction and Hypothesis <p>Patient outcome questionnaires help identify patients with bladder pain syndrome and determine treatment response. Our objective was to compare the readability and understandability of questionnaires assessing bladder pain syndrome.</p> Methods <p>We assessed the readability and understandability of four questionnaires: The O’Leary-Sant, the Pelvic Pain and Urgency/Frequency (PUF) Symptom Score, the Female Genitourinary Pain Index (FGUPI), and the Bladder Pain/IC Symptom Score (BPIC-SS). We used four validated readability calculators: Flesh-Kincaid Grade Score (FKGS), Flesch Reading Ease Score (FRES), Fry Reading Graph Calculator (FRY), and Simple Measure of Gobbledygook (SMOG). The American Medical Association defines readability as a 6th grade reading level. We measured understandability using the Patient Education Materials Assessment Tool (PEMAT). Scores ≥ 70% represented acceptable understandability.</p> Results <p>Only the BPIC-SS met the 6th grade reading standard when evaluated using the FKGS assessment tool. The other questionnaires’ scores ranged from 7th grade to college reading level. When assessing the question section only for each questionnaire, the PUF and BPIC-SS met the 6th grade readability standard. Reduced readability was due to use of polysyllabic words such as “urination” and “frequency,” long questions and answer choices. None of the questionnaires met the PEMAT understandability threshold score of 70%. Reduced understandability was due to confusing structure, failure to define medical terms, and absence of visual aids.</p> Conclusions <p>Questionnaires assessing bladder pain syndrome do not reliably meet recommended standards for patient readability and understandability and therefore may not accurately measure patient responses. These standards should be considered when designing future questionnaires to improve accessibility to all patients.</p>