Regional lymph nodes of the rectum are not demonstrable by pedal lymphoscintigraphy. We have evaluated the technique of rectal lymphoscintigraphy, using a technique similar to that which has been used in the assessment of lymph nodes in breast and prostatic cancer. Thirty-five patients were studied: ten normal subjects and 25 patients with rectal cancer. In normal subjects, the lymph nodes accompanying the superior hemorrhoidal artery and the inferior mesenteric artery are demonstrable in succession; after three hours the aortic lymph nodes are demonstrable. The 25 patients with rectal cancer underwent resection of their primary tumor and the stage was defined according to Dukes (1932). In five patients (stage A) no alteration was demonstrable. In 11 patients (stage B) the demonstration of regional lymph nodes was delayed vs. the control group. In nine cases (stage C) the demonstration of regional lymph nodes was delayed and defective versus the control group.