Type and intensity of tumor-infiltrating lymphocytes (TILs) in close proximity to the primary tumor are prognostically significant in postoperative patients. High intensity of TILs is considered to be a prognostically beneficial factor. The research included 66 postoperative colorectal cancer patients. The control group comprised 20 colon segments. Monoclonal antibodies LCA, CD3, CD4, CD5, CD8, CD20, CD23 and CD138 were used to differentiate between T and B lymphocytes. Types of cells in the infiltrate were defined. We found greater numbers of T and B lymphocytes located in close proximity to the cancerous tissue when compared to the control group. T lymphocyte intensity in the inflammatory infiltrations was directly correlated with the size of resected tumors, presence of regional lymphatic node metastases and histological grade of malignancy. Lymphocytic infiltrations of greater intensity located in close proximity to the primary tumor were found in subjects with less advanced colorectal cancer. The research presented here proves direct dependence between the immune system and colorectal cancer. The presence of lymphocytes in the inflammatory infiltrations located in close proximity to the cancerous tissue has been proved to be prognostically beneficial. The obtained results support the application of immunotherapy in colorectal cancer treatment.