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 on radiology of the colon. However, previous discussions of double contrast ex amination have...