BACKGROUND: Urography(IVU) is considered the best first investigation in patient with suspected urinary calculi, but recently ultrasonography(USG), combined with a plain film of the abdomen, has been suggested as an alternative. METHODS: We undertaken study to see if this approch can be used in emergency patients and outpatients by radiologists with different amounts of ultrasound experence. Some 192 patients with suspected urinary colic presenting to Koo Hospital Emergency Department and Youngnam Universith Hospital outward Department(IM, URO, FM) over 12-month period were studied. They had a plain abdominal film(KUB) and USG examination of the kidney, ureter, bladder following hydration and subsequently underwent IVU. Of these, 22 patients passed a stone before their IVU. The data analysis was performed on the remaining 170 patients. Urography was used as the gold standard. RESULTS: Some 170 patients subsequently underwent IVU at a mean interval of 1.8 days after the ultrasound examination. In 91 of 170 patients the IVU was positive. In 97 of 170 patients the combination of JUB plus USG was positive, leaving three false negative KUB plus USG. Thus the sensitivity of KUB plus USG was 97%, specificity was 89%, positive predictive value was 91%, and negative predictive value was 96%. CONCLUSIONS: Our findings in this study suggest that in the hydrated patient the combination of KUB plus US is a very sensitive and relative specific screening test. Because of the high negative predictive value of KUB plus US, urography is not likely to be helpful when KUB plus US are negative. Urography is indicated only if KUB plus US findings are equivocal or if intervention is necessa.ry.