Real-time ultrasound is a generally available, noninvasive and inexpensive tool allowing evaluation of the thyroid gland without any radiation exposure. The method is highly sensitive with regard to shape, size, localization and morphology of this gland. Owing to low specificity ultrasound does not yield sufficient information concerning the function and degree of malignancy of lesions in relation to the structure and echogenic pattern. In some cases it is possible to achieve the final diagnosis with ultrasound in combination with clinical and laboratory findings. The information is based on the morphology of lesions and is an ideal supplement to the functional information yielded by scintigraphic examination and makes it possible to perform fine-needle biopsy. For primary examination and during follow-up, ultrasound is indispensable as a basic imaging modality. It is extremely important that the physician should be experienced.