The aim of the investigation was an assessment of potentials of computed-tomography colonography (CTC) in diagnosis of diseases of the colon. CTC was made in 125 patients. The investigation was performed after special preparation of the patients for purgation of the colon. The patient was in the supine and prone position. After introduction of room air in the colon the axial sections were laid from the diaphragm cupola to the pelvic floor. The obtained data were estimated and the reconstructions were fulfilled using special software. Pathological alterations or anatomical specific features of the colon were detected in 86 out of 125 cases (68.8%), in 26 of the cases (28.6%) a conclusion was made of malignant tumors in the colon according to the data of CTC. The data obtained by CTC were compared with the data of fibrocolonoscopy, rectomanoscopy, irrigoscopy and histological investigation. In most cases the coincidence of the findings was noted.