This study was undertaken to evaluate the correlation between tumor occupation rate and stage in rectal cancer patients. 210 patients with histologically confirmed adenocarcinoma of the rectum were evaluated. Retrospectively, we divided the subjects' pathological specimens into four groups: group A, tumor occupied less than one fourth of the colic lumen; group B, tumor occupied one fourth to one half of the colic lumen; group C, tumor occupied one half to three quarters of the colic lumen; group D, tumor occupied more than three quarters of the colic lumen. As the tumor occupation rate increased, more invasive cases were observed. Patients of group A had significantly longer survival than those of the other groups. Tumor occupation rates correlated significantly with the Dukes classification (r = 0.546, P < 0.0001). Tumor occupation rate is a primitive method but an easy and inexpensive technique for judging tumor stage. This method can assist in preoperative evaluation, thereby reducing the need for other redundant methods.