From October 1987 to March 1991, 21 (8%) superficial early cancers were found among 256 early colorectal cancers (Dukes A and B1). Superficial early cancers were defined as early cancers less than 3 mm in height. These tumors were found scattered throughout the large intestine and were often observed as reddish spots, which were easily overlooked without careful observation. Histologically, 19 (90%) of them were well-differentiated adenocarcinomas, and five (24%) of them reached the submucosal layer. Eighteen (86%) of them were not associated with adenoma.