A review of 2369 cases of resected primary colorectal carcinoma identified 15 cases of diffusely infiltrating colorectal carcinoma. Depending on the histologic pattern and extent, these cases were classified as linitis plastica (LP) type (seven cases) or lymphangiosis (LA) type (eight cases). The LP type consisted of poorly differentiated adenocarcinoma or signet ring cell carcinoma; it showed an annularly thickened and rigid bowel wall. The LA type consisted of moderately differentiated adenocarcinoma. The colon wall of the LA type was hemilaterally thickened at the mesenteric side. The prognosis was extremely poor for both types. The LP type mainly had peritoneal dissemination (70%), but the LA type frequently had distant metastasis (88%). Early diagnosis and curative operation are important for both types; however, the LA type also requires therapy for distant metastasis.