The value of high resolution real time ultrasound imaging in the preoperative differential diagnosis of focal disease of the parotid gland was evaluated in 35 cases. After description of the ultrasound imaging of the normal gland, the majority of benign and malignant tumours are demonstrated. Ultrasound patterns allow a good differentiation of mixed tumours, warthin's tumours and carcinomas. Differential diagnosis between mixed tumours on the one hand, mucoepidermoid and serous cell adenomas on the other can be difficult or even impossible. This holds true for pathologic lymphomas, too, whereas cysts can be distinguished very well. On the whole, the differentiation between benign and malignant tumours was correct in 28 out of 35 cases. Furthermore, in 21 cases the ultrasound pattern was in accordance with the result of the histologic examination. Compared with sialography, needle biopsy and CT scanning, ultrasonography is a reliable, safe and noninvasive method of high value in preoperative examination of parotid tumours.