In order to elucidate the biological characteristics of colorectal cancer invading the proper muscle, we analyzed DNA ploidy and PCNA labeling index. The growth patterns were divided into three types; those accompanied by intramucosal polypoid growth (PG+), those with non-polypoid growth (PG-), and those ranging between PG+ and PG- (PG+/-). The relationship of DNA ploidy to lymphatic vessel permeation and recurrence was also discussed. The results were as follows: 1) Growth types bore no relation to DNA ploidy and distribution of PCNA. 2) In aneuploidy cancer, it showed a high incidence of lymphatic vessel permeation. A trend of lymphatic metastasis was also observed. Aneuploidy cancer showed a poor prognosis compared with diploidy cancer.