We review here 3 cases of primary thyroid lymphoma that we experienced during the past 5 years (age range: 39-55, all of the patients were female). The clinical and various ultrasonographic characteristics together with the other imaging modalities of primary thyroid lymphomas are described. The clinical features at presentation for one patient were a goiter with rapid growth and this was accompanied by compressive symptoms. The tumors of the other 2 patients were incidentally found during screening thyroid ultrasound exams. The pathologic studies of 2 cases showed a diffuse B-cell lymphoma with associated Hashimoto's thyroiditis and one case was a B-cell lymphoma of the MALT type. An extra-thyroid extension was shown in one case. The treatments included surgery alone for two cases, and chemotherapy and radiation therapy for one case. A US exam of thyroid lymphoma can show various morphological features, and US-CNB is helpful for diagnosing thyroid lymphoma.