Retro- and intra-peritoneal haematomas have been demonstrated in 19 patients by computer tomography. Absorption values varied from 0 to 65 Hounsfield units. Absorption values are high shortly after the trauma, but fall during the following days and weeks because of absorption and enzymatic chances of the haemaglobin and protein. A diagnosis can only be made with a knowledge of the clinical background. Tumours, abscesses and cysts must be considered in the differential diagnosis. Unlike conventional radiography, haematomas can be directly demonstrated by computer tomography. Angiography may demonstrate the point of bleeding when there is no haematoma, or if an haematoma fails to develop because bleeding is taking place into a hollow organ or a duct.