A major limitation in understanding the pathogenetic mechanisms responsible for the intestinal or colonic mucosal injury and dysfunction observed in inflammatory bowel disease (Crohn's disease, ulcerative colitis) is the relative lack of animal models that exhibit the chronic, spontaneously relapsing inflammation associated with these idiopathic diseases. Although no animal model has been developed that possesses all of the pathohistologic features of human inflammatory bowel disease, there are several different models available that exhibit some of the characteristics associated with ulcerative colitis or Crohn's disease. This review will focus primarily on some of the most popular models of intestinal or colonic inflammation induced by exogenous agents. The objective of this review is to critically evaluate each model in terms of its clinical and histopathological features, etiologic mechanisms, and responses to certain drug therapies known to be effective in the treatment of human inflammatory bowel disease.