The use of ultrasound in Crohns disease has a recent history. This method is useful in various situations like: the diagnosis of the disease, the diagnosis of intra-abdominal complications and the follow-up of the operated patient. Moreover, thanks to its practicality of use, ripetibility and accuracy, ultrasounds can represent a first line diagnostic instrument for Crohns disease both in elective and emergency conditions. The authors, in this paper, consider its usefulness and various aspects in these conditions.