Gastrointestinal gas causes distress in many patients and their parents. Most often, patients do not have an actual increase in gastrointestinal gas volume, but rather their complaints derive from a misunderstanding of normal physiology, a misinterpretation of symptoms (colic), or an increase in intestinal sensitivity (irritable bowel syndrome). Symptoms from actual increases in intestinal gas volume are seen most frequently in children who swallow excessive amounts of air, have a dysmotility syndrome, or consume foods containing poorly absorbed carbohydrates. Although many therapies are used in the treatment of gas-related symptoms, under close scrutiny, the commonly recommended agents (e.g. simethicone) do not have proven efficacy. An understanding of the physiology of gas production and disposal is of practical use to pediatricians in determining the appropriate method of intervention for patients with these complaints.