Interstitial cystitis is an inflammatory disease of unknown etiology. To facilitate the study of the pathophysiology of interstitial cystitis, an animal model that correlates with the clinical features of interstitial cystitis and expresses histologic features consistent with those observed in interstitial cystitis patients was developed. Various strains of mice were immunized with a syngeneic bladder homogenate to determine their susceptibility to the induction of autoimmune cystitis. Of 3 mouse strains tested, only the Balb/cAN mice reproducibly developed the clinical correlates and histological features consistent with those observed in interstitial cystitis. In a blinded pathologic review, autoreactive Balb/cAN bladders were correctly distinguished from chronic bacterial cystitis, sham treated bladders and normal control bladders. Edema, fibrosis, perivascular lymphocytic infiltrations and detrusor mast cell accumulation were apparent in 75% of the Balb/cAN mice 2 weeks after immunization and 100% at 4 weeks. These histologic features plateaued and remained stable for at least 6 months. Grossly, the immunized mouse bladders were fibrotic and contracted with a significantly (p <.05) decreased fluid capacity. On hydrodistension, increased vascular prominence and petechial hemorrhage (glomerulations) were evident. Instillation of 14C-urea demonstrated increased permeability in immunized bladders compared with controls. A cellular autoimmune basis for the cystitis is supported by adoptive transfer studies. Spleen cells from experimental mice but not controls transferred the histological features of the disease to naive mice. These studies outline the development of a new experimental autoimmune cystitis model that expresses features similar to those frequently observed in human interstitial cystitis, and may provide a model for the study of the inflammatory process associated with interstitial cystitis. Furthermore, these data suggest a possible role for cellular immune components in interstitial cystitis.