Interstitial cystitis/bladder pain syndrome (IC/BPS) requires validated patient-reported outcome measures; however, no culturally adapted Persian version of the O’Leary–Sant questionnaire is available. We aimed to translate and psychometrically validate the Persian version and assess its measurement properties in Iranian patients.

In this cross-sectional methodological validation study (February–August 2025), the questionnaire underwent forward–backward translation, expert panel review, and pilot testing. Face validity (impact score ≥0.75) and content validity (CVR ≥0.62; CVI ≥0.79) were assessed. Construct validity was evaluated using exploratory factor analysis with varimax rotation. Reliability was assessed using Cronbach’s alpha and test–retest reliability over 15 days.

A total of 100 patients (mean age 56 years) meeting ESSIC criteria were enrolled. The Kaiser–Meyer–Olkin measure was 0.71, and Bartlett’s test of sphericity was significant (χ² = 547.02; p < 0.001). A two‐factor structure explained 64% of the variance comprising a “urinary symptoms” component (loadings 0.77–0.88) and a “pain/distress” component (loadings 0.86–0.87). Internal consistency was good (Cronbach’s alpha = 0.84). In a subgroup of 35 patients, a statistically significant test–retest reliability was seen (ICC = 0.83; 95% CI: 0.77–0.87; p < 0.001).

The Persian version of the O’Leary–Sant questionnaire demonstrated robust psychometric properties, supporting its structural validity and reliability in patients with IC/BPS. The identified two-factor structure, separating urinary symptoms from pain/distress, aligns with the multidimensional nature of IC/BPS and is consistent with prior validations in other languages. This distinction is clinically meaningful, as it reflects different underlying pathophysiological domains and may guide more targeted therapeutic strategies.

The good internal consistency indicates that the items within each domain measure coherent constructs, while the high test–retest reliability confirms the stability of the instrument over time in a clinically stable population. The acceptable KMO value and significant Bartlett’s test further support the adequacy of the dataset for factor analysis and reinforce the validity of the extracted components.

Overall, these findings suggest that the Persian O’Leary–Sant questionnaire is a reliable and valid tool for both clinical assessment and research applications. Importantly, reporting separate subscale scores may enhance sensitivity in detecting symptom changes and improve individualized patient monitoring.

The Persian version of the O’Leary–Sant questionnaire demonstrates satisfactory validity and reliability, supporting its use in clinical practice and research for assessing symptom severity in Iranian IC/BPS patients. Reporting separate subscales (urinary and pain/distress) is recommended for decision-making and monitoring. Future studies should include confirmatory factor analysis, responsiveness, and determination of the minimal clinically important difference.