Interstitial cystitis/painful bladder syndrome affects more than 1 million persons in the United States, but the cause remains unknown. Most patients with interstitial cystitis/painful bladder syndrome are women with symptoms of suprapubic pelvic and/or genital area pain, dyspareunia, urinary urgency and frequency, and nocturia. It is important to exclude other conditions such as infections. Tests and tools commonly used to diagnose interstitial cystitis/painful bladder syndrome include specific questionnaires developed to assess the condition, the potassium sensitivity test, the anesthetic bladder challenge, and cystoscopy with hydrodistension. Treatment options include oral medications, intravesical instillations, and dietary changes and supplements. Oral medications include pentosan polysulfate sodium, antihistamines, tricyclic antidepressants, and immune modulators. Intravesical medications include dimethyl sulfoxide, pentosan polysulfate sodium, and heparin. Pentosan polysulfate sodium is the only oral therapy and dimethyl sulfoxide is the only intravesical therapy with U.S. Food and Drug Administration approval for the treatment of interstitial cystitis/painful bladder syndrome. To date, clinical trials of individual therapies have been limited in size, quality, and duration of follow-up. Studies of combination or multimodal therapies are lacking.