We evaluated the computed tomographic (CT) features of small bowel (SB) ischemia and necrosis and correlated the findings with clinical outcome or patient prognosis. Sixty-eight surgically or angiographically proved cases of SB ischemia were retrospectively reviewed. The CT features of intestinal ischemia were divided into three groups: (A) thinned bowel wall with poor enhancement, intramural gas, or portal venous gas; (B) thickened SB wall without superior mesenteric vein thrombosis; and (C) thickened SB wall with superior mesenteric vein thrombosis or intussusception. The evaluated factors included bowel wall or mucosal enhancement pattern, SB dilatation, mesenteric edema, and CT evidence of narrowing or occlusion of the superior mesenteric artery or vein. The bowel necrosis rates and mortalities were compared with chi-square test. Oral contrast material was not administered. Intramural gas and SB dilatation were associated with a higher bowel necrosis rate (eight of eight, 100%, and 17 of 21, 81%, respectively) in group A. Poor mucosal enhancement of the thickened bowel wall indicated a higher bowel necrosis rate in groups B (six of seven, 86%) and C (12 of 12, 100%) than did normal mucosal enhancement. Only intramural gas was accompanied with a higher mortality (six of eight, 75%). Intramural gas of a thinned bowel wall and poor mucosal enhancement of a thickened small bowel wall are useful signs of bowel necrosis. Intramural gas would indicate poor patient prognosis.