Fifty colorectal carcinomas were investigated to demonstrate distal intramural spread (DIS). In 17 cases (34%) a DIS ranging from 0.25 to 3.5 cm was present. DIS was positively correlated with stage C2 (p less than 0.01), lymph node metastasis (p less than 0.03) and infiltrative growth of the tumor (p less than 0.05). Our results show that DIS is a relatively frequent event but of limited extension. In fact, a distal clearance margin of 2 cm was considered safe for all patients but one C2 mucoid case. No pathologic feature can predict preoperatively the presence and extent of DIS.