Because Crohn disease can occur at any location in the gastrointestinal tract, upper and lower endoscopies allow for the visual examination of the mouth, esophagus, duodenum, terminal ileum, and colon as well as for the performance of biopsies that may show typical granulomatous changes on histology. Capsule endoscopy allows direct visualization of the small intestine, although it should be avoided in patients with intestinal strictures. Use of barium contrast agents in the small intestine provides for an adequate study to evaluate for small-bowel disease. Computed tomographic and magnetic resonance enterographic images of the small intestine can show mucosal and mural edema and can also show complications such as abscess formation. Magnetic resonance enterography also has the benefit of no ionizing radiation, which can become significant in patients with Crohn disease who undergo multiple computed tomography and fluoroscopic imaging of the abdomen. Unfortunately, to our knowledge, no imaging study is currently specific enough to confirm a diagnosis of Crohn disease. Current laboratory methods for evaluating possible Crohn disease, such as elevated levels of fecal calprotectin, neutrophil-associated protein, and serum antibodies to Saccharomyces cerevisiae, are more useful to support the diagnosis, rather than serve as a diagnostic test, because of poor sensitivity and specificity.