Echography enables a useful diagnostic distinction to be drawn between solid structures and cysts in the thyroid. Cold nodes measuring 1-5 cm in diameter, cysts (rarely malignant), and solid formations (more commonly malignant) can be differentiated to facilitate diagnosis, while changes in the size of a node can be followed without interrupting drug treatment to determine whether they are due to haemorrhage, resolution of a process, or an increase in node tissue. There is no risk to the patient and the cost of the examination is negligible. Its utility in the initial and subsequent investigation of such nodes is asserted.