Ultrasound screening of the abdomen, the basal segments of the pleural cavities and the deep leg veins was performed in 637 patients in a medical intensive care unit. The findings were classified into significance groups (SG) depending on their clinical relevance (SG 1: crucial; SG 2: of immediate relevance; SG 3: of future relevance; SG 4: of no significance). The investigation was indicated in 172 patients (27%-Group 1), in the other 465 patients (73% - Group II) it was performed despite the absence of indications. Abnormal findings were discovered in 156 patients of Group 1 (90.7%) and were classified under SG 1 in 29.7% of them. SG 2 in 43%, SG 3 in 14.5% and SG 4 in 3.5%. In Group II, abnormalities were noted in 70.1% of the patients, and were assigned to SG 1 in 4.3%, SG 2 in 5.4%, SG 3 in 32.5% and SG 4 in 27.9%. The most frequent significant finding in Group II was deep leg vein thrombosis. In both groups the organ most frequently showing abnormal findings was the liver (41%), followed by the gall bladder (27%) and the kidneys (20.5%), though most of them were insignificant findings of no relevance to the situation at the time and were classified under SG 3 and 4 (34%, 25% and 20% of the subjects examined). After excluding the findings in the pleural cavities (14.1%), aorta (3.4%) and biliary tract (1.2%), most of the findings noted in other organs or regions of the body (leg veins 11.1%, intestine 8.8%, spleen 8.3%, peritoneal cavity 7.2%, pancreas 1.7%) were assigned to SG 1 or SG 2. These results show that, despite the numerous irrelevant findings which it throws up, ultrasonography is of great diagnostic value and should be extensively employed.