Computed tomographic colonography (CTC) has the potential to become an accepted technique for detecting of colorectal cancer.The aim of the study was to evaluate usefulness of CTC in preoperative evaluation of colorectal tumors and the regions of colon endoscopically unavailable.Material and methods. A total of 49 patients with colorectal tumors identified at conventional colonoscopy were included. In all these patients CTC was performed and results were compared with colonoscopy. In addition in CTC infiltration of surrounding tissues, organs, lymph nodes and liver were assessed. Findings were compared with contrast-enhanced CT of abdomen.Results. Colonoscopy was completed to the caecum in 24 (48.9%) patients. CTC failed only in one patient. CTC was congruent with colonoscopy in evaluation of tumor location and morphological type. In CTC two additional tumors were found proximately to occlusive masses, it is in endoscopically unavailable regions. Sensitivity and specificity of CTC comparing to CT in diagnosis of fat tissue infiltration and surrounding organs infiltration at the site of tumor were 95.5% / 50% and 100% / 86.9% respectively. Concordance of results in evaluation of lymph nodes was 93.9% while sensitivity and specificity for CTC was 84.6% and 100% respectively. Concordance of evaluation of liver metastases was 78.8%, while sensitivity and specificity for CTC was 61.5% and 90% respectively.Conclusions. CTC is a useful method in diagnostics of colorectal tumors. It allows to diagnose tumor, determine local tumor staging and detect synchronous lesions in endoscopically unavailable regions.