Background:Pathogenic mechanisms responsible for the undulating symptom pattern, or indeed causative agents for the development, of inflammatory bowel diseases [IBD] are largely unknown. Many physicians and most patients are convinced that stress affects the course of IBD. As with most factors that contribute to IBD, it is unclear whether stress merely exacerbates established disease or indeed contributes to the development of disease. We designed this study to investigate whether stress induces or aggravates colitis in interkeukin-10 knockout [IL-10 ko] mice and to determine the role of intestinal permeability in this model of stress-related colitis.