Sudan Black B and Sudan Blue can partly enter the lymphatics of the small intestine from the lumen with long chain fatty acids. By use of a fat emulsion saturated with them small intestinal and mesenteric lymphatics were clearly delineated. Subserosal and mesenteric lymphatics of the small intestine appeared as blue lines. With this method we studied anatomical changes of the lymphatic vessels during the development of cancer. As experimental tumor VX2 carcinoma was used. Lymphatic vessels were not be found in cancerous regions by this lymphangiographic procedure, even in the early stages of cancer. Lymphatics passing through the tumorous tissue were completely obstructed and accompanied with peripheral dilatation. Compared to the morphological changes of the blood vessels, which were studied microangiographically, the lymphatic vessels were more easily affected by the malignant growth.