The purpose of the research is to study the criteria for evaluating the regression of malignant rectal tumors after neoadjuvant therapy. 103 patients with the established diagnosis of the rectal cancer were involved in a research. To assess the extent of tumor regression, the Rectal Cancer Regression Grade (Wheeler) scale was used. All materials removed during surgery were analyzed using visual-microscopic and microscopic examination.We examined 103 patients diagnosed with cancer of various parts of the rectum. Observations were carried out between 2010 and 2015 on the basis of Clinical Hospital No.1 (Azerbaijan Medical University), as well as in the ELMED Medical Center. Patients were divided into 2 groups: 1) patients who underwent total open mesorectumectomy (OSTM) - (n=56); 2) patients to whom TME was performed by laparoscopic method (LTME) - (n=47).