43 Holstein-Friesian cows were investigated by sonography for the occurrence of a displacement of the abomasum. 26 animals suffered from a displacement of the abomasum. The results of sonography of these diseased and of healthy animals are described. After sonography all animals were subjected to an exploratory laparotomy in order to check the validity of the sonographic diagnosis. The results and the diagnosis obtained by laparotomy were compared to the sonographic findings.