OBJECTIVE: To evaluate the value of virtual colonoscopy in diagnosis of colorectal neoplasia. METHODS: Virtual colonoscopy was performed in 29 patients with colorectal neoplasia confirmed by colonoscopy. The results were compared with colonoscopy for each case. RESULTS: Virtual colonoscopy was successfully performed in each patient without any complications. All colorectal carcinomas detected by colonoscopy were identified by virtual colonoscopy. Twenty-five polyps were detected with colonoscopy, whereas only 16 identified by virtual colonoscopy. Compared with the results of colonoscopy, detection rate of polyps greater than 1.0 cm between 0.5 approximate, equals 0.9 cm and less than 0.5 cm in size was 90.0% 62.5% and 28.6% respectively. CONCLUSION: Virtual colonoscopy is fast, minimal invasive and well tolerated. This technique is a valuable clinical method in diagnosis of colorectal cancer and polyps larger than 0.5 cm in size.