OBJECTIVE: To investigate the ultrasound manifestations of primary thyroid lymphoma. METHODS: The ultrasound manifestations of 20 cases of primary thyroid lymphoma in our hospital were retrospectively analyzed. Results: All 20 cases of primary thyroid lymphoma showed posterior echogenicity (20/20, 100%) and 17 cases (17/20, 85%) showed enlarged thyroid gland. 13 cases (13/20, 65%) showed single or multiple hypoechoic nodules with irregular borders and posterior echogenicity, which were classified as nodular. 3 cases (3/20, 15%) showed enlarged thyroid gland on one side with hypoechogenicity and posterior echogenicity, which were classified as nodular. Four cases (4/20, 20%) presented between the first two types of manifestations, similar to Hashimoto’s disease, with heterogeneous echogenicity, lamellar hypoechogenicity, and posterior echogenicity, which was classified as a mixed type. Conclusion: Primary thyroid lymphoma has a variety of ultrasound manifestations, with enlarged thyroid gland and posterior echogenic enhancement of the lymphoma lesion being its main ultrasound features.