Abstract: Cancerous tissue lymphocytes were counted for 18 specimens of large bowel cancer after the-mochemotherapy and 18 on operation alone. Cancerous tissue lymphocytes were also counted be-fore heat for 9 cases of thermochemotherapy group. Results appeared that difference of cancerous tissue lymphocytes was highly significant statistically in thermochemotherapy group and operative group (P<0.01). Lymphocytes after thermochemotherapy were more marked than those before thermochemotherapy, difference was also highly significant statistically (P<0. 0l)" The results indicated that thermochemotherapy can increase infiltrating lymphocytes inside cancerous tissue. Increase of infiltrating lymphocytes might prolong survival term of patient with cancer.