New rodent models of chronic intestinal inflammation are mediated by a TH1-cell and macrophage dominated immune response to luminal bacterial constituents. The pathology of these spontaneous and induced models differ widely and caution is needed when assessing the comparative aspects of such animal models and human inflammatory bowel diseases (IBD). Considerable immunological and therapeutic evidence suggests that chronic and immune-mediated models are relevant in human IBD and that pathogenic principles are similar. However, animal models have not been able to duplicate exactly the pathological characteristics of ulcerative colitis or Crohn's disease, indicating a need for caution in extrapolating data from experimental models to human IBD.