Objective: To examine the association between chronic spontaneous urticaria (CSU) and interstitial cystitis/bladder pain syndrome (IC/BPS). Methods: A population-based retrospective cross-sectional study was performed using the Clalit Health Services medical database. The prevalence of CSU was compared between patients diagnosed with IC/BPS and age- and gender-matched controls. Univariate analysis was performed using Chi-square and Student t test and a multivariable analysis was performed using a logistic regression model. Results: The study included 681 patients with IC/BPS and 3376 demographically matched controls. The mean age of IC/BPS patients was 60 years old. The prevalence of CSU among patients with IC/BPS was higher as compared to the control group (20% vs 13.7%; P <.001). The adjusted OR for CSU in patients with IC/BPS was 1.58 (95% CI 1.28-1.97). Female gender and Jewish ethnicity were associated with the coexistence of these disorders (OR 1.7 95% CI 1.36-2.13, and 1.6 95% CI 1.28-2, respectively). Conclusion: A significant association was found between IC/BPS and CSU. This finding may support the presence of allergic/immune components in the pathogenesis of IC/BPS.