111Indium (111In) WBC scintigraphy is an accurate method of assessing the extent of inflammatory bowel disease. A prospective study was performed to determine the correlation of ultrasound scanning with 111In WBC scintigraphy in the assessment of inflammatory bowel disease. Eighty-three indium and ultrasound scans were performed in 57 patients. Forty-six patients had Crohn's disease and 11 patients had ulcerative colitis. The site extent of abnormality and the appearance of the bowel were recorded and compared to the findings on indium scintigraphy. Ultrasound detected 84% of indium-positive sites. If the rectum was excluded, sensitivity of detection rose to 91%. Three percent of indium-negative sites were positive on ultrasound.