Autopsy evidence of gross or microscopic GI involvement can be found in up to 51% of all lymphoma cases. In descending order of frequency the stomach, small intestine, colorectum, and esophagus may be involved. Radiologically, GI lymphomas tend to have similar morphologic characteristics regardless of their site of origin. Additionally, the diverse radiologic manifestations may mimic a variety of diseases. Nevertheless, growing clinical experience and improvements in imaging techniques have increased the frequency with which the proper diagnosis can be suggested. The extramucosal origin of a mass or masses is often detectable by double-contrast examination and dictates a diagnostic spectrum fundamentally different from that of tumors arising from the mucous membrane. Similarly, the ability of CT to determine the wall thickness of the involved segment and its relationships to adjacent structures has further increased radiologic specificity. These capabilities are important, not only from the diagnostic standpoint, but also with respect to staging, prognosis, and, ultimately, increased survival.