The value of 99mTc-hexamethylpropyleneamine oxime (HMPAO) leukocyte images has been confirmed in patients with Inflammatory Bowel Disease. We performed 121 scintigraphic examination. The results were evaluated by radiologic and/or endoscopic examinations. The patients were divided into three subgroups: A) patients with active disease and less than 15 days of corticotherapy (n = 42). B) patients with active disease and more than 15 days of corticotherapy (n = 31). C) asymptomatic patients (n = 48). Over all sensitivity and specificity were 86% and 92.2% respectively. The sensitivity in subgroup A was 97.5% and 70% in the subgroup B. In the subgroup A the isotopic study showed the entire area of active inflammation in 95% (38/40) and colonoscopy in 32.5% (13/40). The leucocyte scanning showed clear pathologic activity in the ileum with a sensitivity of 86%. We conclude that 99mTc-leukocyte scintigraphy is the best method to assess the location of active inflammation in patients with less than 15 days of treatment. Scintigraphy was best in the assessment of active disease especially in Crohn's disease of the small bowel.