The experience accumulated in daily abdominal CT scanning and CT evaluation of gastrointestinal lesions has generated helpful technical guidelines and some reliable principles of interpretation. These general principles are briefly discussed in this review, and the importance of performing a CT examination that is adequate for the detection and evaluation of gastrointestinal lesions is stressed. CT features useful in differentiating benign from malignant lesions, limitations and pitfalls in CT interpretation, overlap in the CT appearance, and classical CT features leading to specific diagnoses are described and illustrated. Although CT is established as one of the most important techniques for imaging the gastrointestinal tract, it should be used selectively and only in the context of appropriate clinical and conventional radiologic examination. CT should not be regarded as competing with, but as complementing, barium examination of the gastrointestinal tract.