Acute intestinal ischaemias, which are associated with a high mortality of 70-90 per cent, are properly identified in only about 50% of the cases despite the use of update imaging methods. Improvement of the unfavourable prognosis appears possible if diagnosis is effected early enough. With the help of high-resolution real time sonographic equipment--as far as possible with 5 MHz linear or convex transducers--ischaemic changes of the intestinal wall can be detected. However, a sophisticated examination technique is necessary. The following findings must be sought for, depending on the degree of severity and the stage of the mesenterial disturbance of blood flow: Oedematous swelling of the intestinal wall; intramural air ("pneumatous intestinalis"); free liquid; free air; possibly also air in the portal venous system. If the conditions of examination are favourable, it is also possible to identify the relevant stenose or occlusions at the mesenteric vessels by means of Duplex sonography. Sonography is well suited for acute diagnosis and follow-up assessment of intestinal flow disturbances. Angiography should be used preoperatively and to clarify the problem of non-occlusive types of intestinal ischaemia.