Abdominal sonography represents the diagnostic method of choice in case of acute abdomen. On the bases of their experience on more than 1200 consecutive examinations performed in case of acute abdomen the author evaluate the fields of application of sonography in acute patients. A decisional algorithm in trauma patients based on sonographic results is presented. The actual indications of sonography abdominal non traumatic pathology are presented: paying particular attention to acute gastro-intestinal diseases. The therapeutic role of interventional sonography in the acute abdomen is also discussed.