It is a great pleasure for me to introduce and to recommend this much needed text on double contrast examination of the colon. It is aimed both at clinicians who request X-ray examinations of the colon and at radiologists who must per form and interpret these studies. Over the past decade there has been renewed interest in X-ray examination of the colon despite the tremendous advances in endoscopy and imaging tech nology. This renewed interest is evidenced by the proliferation of new books...