We aimed to determine the activity of Crohn's Disease (CD) and Ulcerative Colitis (UC) with this radiotracer and to compare it with the normal clinical indexes. 32 patients with CD (19 women) and 18 with UC (13 women) were studied and a sequential abdominal 99mTc-HMPAO-label leukocyte scintigraphy was performed after evaluating the activity clinical scales indexes (Harvey's for CD and Lictiger for UC). Quantification was performed to obtain intestinal activity indexes in regards to intestinal uptake with background, bone marrow, liver and spleen, comparing them with the clinical indexes. In CD, all scintigraphic indexes showed a significant correlation (p < 0.001) with clinical activity. The best results were obtained with gut/background (r: 0.73) and gut/bone marrow (r: 0.72). In UC, we obtain a lower correlation between clinical and scintigraphic indexes. Significant correlations (p < 0.05) were only found with the gut/background (r: 0.52) and gut/bone marrow growth indexes (r: 0.58). The others showed no correlation. In conclusion, IBD activity estimated with 99mTc-WBC and scintigraphy indexes showed moderate correlation with clinical scales. However, the information of the scintigraphy was very useful in the management of these patients.