Portomesenteric pneumatosis has been traditionally associated with intestinal infarction and poor outcome; however, recent studies have questioned its clinical value. To assess its diagnostic and prognostic significance we have retrospectively evaluated 47 patients correlating the CT finding of portomesenteric vein gas with clinical data and outcome. Thirty-nine patients (83%) had surgical evidence of intestinal infarction, four had necrotic small bowel volvulus (8.5%), two had blunt trauma, one had necrotic gastric volvulus, and one a gastric mucosal lesion induced by a nasogastric tube. Fifteen patients survived (31.9%); only 8/39 patients with intestinal infarction survived. Portomesenteric pneumatosis is a reliable marker of intestinal infarction and poor outcome; however, in trauma patients this sign is associated with a better prognosis.