The findings of ultrasonic examination in bone and soft tissue tumours are evaluated for their usefulness in preoperative tumour diagnosis, with particular reference to size, demarcation, structure, as well as the topographic situation of the tumour. Furthermore, the results of ultrasonic tomograms are compared with those of X-rays and angiography. It seems that this simple method, which is without risk to the patient, is a valuable additional investigation in the diagnosis and therapy of tumours of bone and soft tissue.