Over 90% of children with chronic abdominal pain will fit the diagnostic criteria for a functional gastrointestinal disorder (FGID). (5) As defined by Rome criteria, the FGIDs are a set of diagnoses with specific symptom profiles in the absence of structural or biochemical abnormalities to explain symptoms. FGIDs related to chronic or recurrent abdominal pain include irritable bowel syndrome (IBS), functional dyspepsia (FD), functional abdominal pain (FAP), and abdominal migraine. (6) FGIDs are probably best understood utilizing a biopsychosocial model which states that abdominal pain occurs as a result of varying contributions from, and interactions between, biological factors, psychological factors, and social factors. The biological factors most implicated in the generation of abdominal pain include motility disturbances, visceral hypersensitivity, and inflammation. Stress/anxiety is the most implicated psychologic factor. Anxiety may interact with both motility and inflammation. For example, the investigators have demonstrated an association between anxiety and mucosal mast cells in children with post-prandial distress syndrome, a subcategory of FD. (7) The scaffolding for the interaction between the various factors has been termed the brain-gut axis consisting of both neural and humoral pathways.