Background: Recent data have shown that bowel wall thickness andmesenteric blood flow rates are significantly increased in active IBD,suggesting that bowel wall thickness and mesenteric flow may be a useful, noninvasive index of disease activity. Aim: the aim of this prospective study is toevaluate the use of conventional ultrasound and color Doppler as tools of IBDdiagnosis and activity. Subjects and Methods: patients having active IBD(n=40), non IBD colonic disease (n=10) and control subjects with normal colon(n=10) were evaluated. The lab investigations, colonoscopy, conventionalultrasound and color Doppler for SMA, IMA and PV parameters wereevaluated. Ten of the IBD were re-evaluated after remission. Results: The IMAparameters significantly differed (increase of diameter, PSV, EDV and bloodflow volume, and decrease of RI and PI) in left ulcerative colitis (UC), pan UCand Crohn’s disease (CD) subgroups compared to control subjects; while SMAparameters were different only in pan UC subgroup. In the UC subgroup thebowel wall thickening did not decrease after quiescence in contrast to the CDpatients in remission. The portal vein diameter, velocity and blood flowvolume did not differ in active IBD patients compared to non IBD patients butshowed significant decrease with remission. After entering in remission all IBDpatients who could be followed showed significant difference in all vascularparameters. Conclusion: Conventional ultrasound has a modest accuracy indetecting ulcerative colitis lesions. It is more accurate to detect left colitiscompared to pancolitis. Its accuracy is very high in detecting terminal ileallesions in Crohn's disease. All the assessed vascular parameters of the superiorand inferior mesenteric arteries proved to be useful in detecting ulcerativecolitis and Crohn's disease lesions as well as to detect remission in followed upcases. The SMA vascular parameters are of value to differentiate between leftand pan ulcerative colitis.