Abstract: Background: this report describes our experience in CT-perfision (CTP) use for evaluation of rectal tumors neoadjuvant treatment effectiveness. Tumor response for combination of radiation and chemotherapy was related to CTP pattern. Material and Methods: five patients aged 48 - 62 years with rectal adenocarcinomas histologically verified (4 patients of T3N0M0 stage and 1 patient T3N1 M0) were included. All of them had combined neoadjuvant radiotherapy and chemotherapy followed by surgery. Before and after neoadjuvant treatment virtual colonoscopy (VCS) with CTP was done in all the cases prior to surgical intervention. Results and Conclusions: comparing perfusion pattern in rectal tumor and in normal tissue, we saw blood volume (BV) to be significantly increased, and mean transit time (MTT) moderately shortened in tumor tissues. Tumor tissue BV in neoadjuvant therapy responders was much higher than in those for whom the therapy appeared to be ineffective. On combination of radio- and chemotherapy, BVin tumor tissue significantly decreased, and MTT elongated. References 1. Bosset J."F. et al. Chemotherapy with Preoperative Radiotherapy in Rectal Cancer. N. Engl. J. Med. 2007; 357 (7): 728. 2. Чиссов В.И., Дарьялова С.Л. Избранные лекции по клинической онкологии. М.2000; 736. 3. Bellomi M. et al. CT Perfusion for the Monitoring of Neoadjuvant Chemotherapy and Radiation Therapy in Rectal Carcinoma. Initial Experience. Radiology. 2007; 244: 486-493. 4. Sahani V. et al. Assessing Tumor Perfusion and Treatment Response in Rectal Cancer with Multisection CT. Initial Observations. Radiology. 2005; 234: 785-792. 5. Yee J. Virtual colonoscopy. Ed. by Galdino G.2008; 219. 6. Хомутова Е.Ю. и др. Устройство для раздувания толстой кишки. Патент на полезную модель № 71072 от 14-05-2007 г. 2008. 7. Силантьева Н.И., Цыб А.Ф. и др. Компьютерная томография в онкопроктологии.М.: 2007; 144.