The small intestine of 50 cows was examined ultrasonographically with a 3.5 MHz linear transducer. The cows were examined on the right side, from the tuber coxae to the eighth intercostal space and from the transverse processes of the vertebrae to the linea alba. The appearance of loops of small intestine and their contents and motility were assessed. In the majority of cases, the intestine contained feed and the contents appeared hyperechoic, but in some cows, the intestinal lumen contained mucus or fluid which was hypoechoic. The cranial part of the duodenum could be viewed longitudinally and in cross-section: its largest diameter varied from 1.1 to 5.4 cm and it could be identified with certainty only medial to the gall bladder, which served as an acoustic window. The descending part of the duodenum was adjacent to the abdominal wall and was enveloped in the hyperechoic greater omentum, differentiating it from the jejunum and ileum. The largest diameter of the descending part of the duodenum varied from 0.9 to 3.7 cm. The ascending duodenum could not be identified because of its anatomical position. Loops of jejunum and ileum were usually viewed in cross-section and sometimes longitudinally; in contrast with the duodenum, they were constantly moving. The average diameter of the jejunum and ileum varied from 2.2 to 4.5 cm.