Accurate, inexpensive, non-invasive studies in evaluation of inflammatory bowel disease (IBD) would represent a significant advancement in identifying and measuring disease activity. There is new evidence that positron emission tomography (PET) scanning can fulfill many of these criteria. The aim of this review is to report the studies pertaining to the use of PET in IBD and provide an evidence-based approach on how to use PET clinically in IBD. Searching Medline and the Cochrane Database of Clinical Trails on July 18, 2008 identified 12 relevant manuscripts for review. Types of studies of PET in IBD include the incidental identification of IBD during studies performed for other indications, the evaluation of suspected IBD and the assessment of known IBD. PET has been studied in both children and adults and has shown excellent sensitivity for detecting active bowel inflammation, but with poor specificity in some studies. PET alone appears sufficient for the evaluation of ulcerative colitis, but PET/computed tomography provides considerably more information over PET alone in the evaluation of Crohn's disease. Current clinical applications for PET in IBD include its use in the early evaluation of IBD, especially in children who may not tolerate an invasive test such as colonoscopy; and its use in differentiating between a flare of IBD versus the onset of a non-inflammatory process causing similar symptoms in patients with known IBD. Many unanswered questions remain, but PET appears to be a promising tool in the non-invasive evaluation of IBD.