Evaluation of extension and complications as well as assessment of Crohn's disease activity, include different diagnostic methods, of which many utilize ionizing radiation. In our routine work, high resolution B-mode and Doppler ultrasound with measurements of bowel wall thickness and hyperemia, as well as calculation of resistance index of mural arteries and visualisation of extramural changes, represent valuable diagnostic tools in screening, assessment of disease activity, and follow up of the patients with Crohn's disease. Therefore, we reduce the use of ionization radiation in diagnostic workup, which is particulary important considering the fact that Crohn's disease predominantly affects young patients.