The aim of this study was to compare the results obtained with an indium-111 scan with those obtained with less expensive and harmless ultrasonography to evaluate the location and inflammatory activity of Crohn's disease. Thirty-one patients previously studied with x-ray underwent abdominal 111In scans and ultrasonography (US). Sensitivity and specificity of US in detecting lesions seen with 111In scan were 77% and 92.8%, respectively. Sensitivity and specificity of 111In scan in detecting x-ray-defined lesions were 69.2% and 92.7%; the figures for US were 73% and 93.3%, respectively. Considering the evaluation of disease activity, ultrasonographic bowel wall thickness was significantly related to scintigraphic intensity of emission (r = 0.75 P < 0.01). Our experience suggests that US provided information about the location and inflammatory activity of lesions similar to that obtained from 111In scan.