Emerging evidence has demonstrated that protein misfolding in the endoplasmic reticulum (ER), i.e., ER stress, plays fundamental roles in IBD development in humans. Patients with active Crohn’s disease and ulcerative colitis exhibit signs of ER stress in their ileal and/or colonic epithelium. Human genetic studies of IBD have identified primary genetic abnormalities in several genes that encode proteins associated with ER stress. We recently reported that oral delivery of tauroursodeoxycholic acid (TUDCA), a naturally occurring bile salt proven to reduce ER stress both in vitro and in vivo, dramatically decreases the clinical, histological and biochemical signs of inflammation in four different IBD mouse models through reducing ER stress in colonic epithelial cells.