In the past few years, several studies have assessed the visualization of digestive diseases by ultrasound, but its clinical accuracy has been rarely defined. Thus we evaluated the contribution of sonographic examination as an initial diagnostic mean in the detection of colonic lesion. During a period of thirty six months (June 85-June 88) when we performed a standard sonographic abdominal examination, we utilized ultrasound to look for thickening or other modifications of the large bowel wall, if the clinical findings suggested a colonic disease. In these conditions we performed 453 US examinations. In our study, 363 cases were considered to be negative and the controls demonstrated colonic wall lesions in 24 cases. Thus the sensitivity was one of 77%. The sonographic examination was positive in 90 cases with 6 false positives. Thus our specificity reached 98.2% and the accuracy achieved was 93.3%. Thus sonographic examination appears to be a rapid, non invasive, mobile, mean of examining the abdominal cavity and also the large bowel in all patients. If this examination is negative, a colonic disease is possible since sensitivity is 77%. On the other hand, if the examination is positive, a colonic disease is very probable, since specificity reached 98.2%. The accuracy of US Colonic examination is 93.3% and with using abdominal plain film, theses percentages may be improved.