Background: Psychological comorbidities have been reported in patients with hidradenitis suppurativa (HS), yet only a few studies have investigated the possible association between HS and severe psychiatric disorders. The current study aimed to assess the association between HS and bipolar disorder, a major, chronic, psychiatric disease. Methods: A nationwide, population-based study was performed utilizing data from the Clalit Health Services (CHS) database in Israel. The study included 4,191 HS patients and 20,941 ageand gender-matched controls. A multivariate binary logistic regression, adjusted for demographic and behavioral risk factors, was performed. Results: A higher proportion of bipolar disorders was found among HS patients compared to controls (0.7 vs. 0.1%, respectively). There was an increased proportion of active smokers among HS patients than among controls (53.4 vs. 13.5%, respectively). In the multivariate analysis, adjusting for age, sex, and smoking, HS was found to be independently and positively associated with bipolar disorders (OR 2.12, 95% CI 1.21-3.27, p < 0.01), yet after controlling for body mass this association became nonsignifi-cant. Conclusions: Bipolar disorders are associated with HS. Future studies should explore whether cardiometabolic deficiencies might account for this association. Healthcare providers should consider this potential co-occurrence as it may impede patient compliance and require appropriate screening and treatment. Results also stress the need for a multidisciplinary approach to optimize management of the disease and its associated comorbidities.