Compare the two series of pictures. The clinical presentation was almost the same in these two cases. Patients were referred for an evaluation of clinical and biochemical hyperthyroidism. The FT4 level was more than double of the upper normal limit in both cases. Patients had neither pain or tenderness, nor subfebrility or fever, nor eye complaints. The only difference was the ultrasonographic pattern. The patient with Graves' disease had diffuse hypoechogenicity and substantially increased thyroid blood flow. However, the patient with de Quervain's thyroiditis had a patchy hypoechogenic pattern and decreased blood flow.