Fifty patients with no small-bowel disease were evaluated by CT to determine the normal appearance of the small bowel and mesentery. Subsequently, the CT findings in 95 patients with proven small-bowel disease were analyzed to determine which CT observations correlated with neoplastic, inflammatory, or edema-producing processes. Thirty-three (83%) of 40 patients with wall thickening or mesenteric masses > 1.5 cm had a neoplastic process. Twenty-eight (82%) of 34 patients with normal mesenteric fat attenuation, wall thickening < 1.5 cm, or mesenteric masses < 1.5 cm had inflammatory disease. Fourteen (67%) of 21 patients with no mesenteric mass, increased mesenteric fat attenuation, and wall thickening < 1.5 cm had noninflammatory edema. Overall, CT assigned 75 (79%) of 95 patients into appropriate categories; use of ancillary CT findings led to correct categorization in 83 (87%). CT is helpful in correctly assigning a disease category to patients with small-bowel wall thickening.