Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD), are chronic relapsing inflammatory conditions of the gastrointestinal tract. IBD is thought to result from a complex interaction between genetic, immune, microbial and environmental factors. The role of vitamin D in bone health and calcium homeostasis is well documented. However, emerging data suggests that vitamin D may also regulate immune responses, which may play a role in the pathogenesis and disease activity of IBD.