It was reported that lymphoid infiltration (LI) of colon cancer tended to be found more commonly in patients with colonic cancer in an early stage than in an advanced stage. This time, the correlation among LI of colon cancer, cell-mediated immunity and the cumulative 5-year survival rate was studied in 124 patients with resected colon cancer. The results were as follows: 1) The cumulative 5-year survival rate in patients with positive LI was higher than that in the patients with negative LI. 2) There was correlation between the degree of LI of the cancer and Su-PS skin reaction. 3) Postoperative cell-mediated immunity was reduced in the cases of poor prognosis. Therefore we insist on paying attention to immunochemotherapy for 24 months after surgery.