Cyclosporine A had a high success rate for patients with Hunner lesions in whom more conservative options, including endoscopic treatment, had failed. The success rate was low for patients without Hunner lesions. A 3 to 4-month trial is sufficient time to assess response. Adverse events were common and led to discontinuation of cyclosporine A for some patients. Close monitoring is needed, especially for blood pressure and renal function.