The diagnostic value of virtual colonoscopy versus colon oscopy was compared in detection of colorectal neoplasia. Virtual colonoscopy wa s performed on 29 patients with suspected colorectal diseases, Results were comp ared with colonoscopy for each case. Virtual colonoscopy was successfully perfor med on each patient. All patients tolerated virtual colonoscopy well, had no com plications. All colorectal malignance were identified both by virtual colonoscop y and colonoscopy. Twenty-five polyps were detected with colonoscopy, whereas o n ly 16 polyps were defined by virtual colonoscopy. Detection rates of polyps grea ter than 1.0 cm,between 0.5-0.9 cm and less than 0.5 cm in size were 90%,62.5% a nd 28.6% respectively. Virtual colonoscopy is fast, minimally invasive and well tolerated. This technique is a valuable clinical method in diagnosis of colorect al malignance and polyps larger than 0.5 cm in size.