Primary thyroid lymphoma is a rare disease that accounts for about 5% of all thyroid neoplasms. It shows a female predominance, especially in women with a pre-existing Hashimoto.s disease. During a 15-year period, 11 patients were diagnosed with primary thyroid lymphoma at Department of Endocrinology, Diabetes and Metabolic Diseases, Sestre milosrdnice University Hospital. There were no records on associated Hashimoto.s thyroiditis in any of them, which is inconsistent with the international literature reporting on such association in 40%-80% of cases. Painless neck edema was the most common physical symptom for patient presentation. The diagnosis was based on fine needle aspiration cytology, while the spread of disease to other organ systems was ruled out by other studies (computed tomography, ultrasonography and gallium scintigraphy). However, it should be noted that diffuse or nodular lymphoma cannot always be classified only by aspiration cytology. The World Health Organization classification was used. Today, it has been generally accepted that thyroid lymphomas belong to a group of lymphomas associated with mucosa-associated lymphoid tissue (MALT). The most common form of nonHodgkin's lymphoma (NHL) of the thyroid was B-cell phenotype lymphoma with a high malignancy grade. All patients were treated with chemotherapy according to the CHOP protocol (cyclophosphamide, doxorubicin, vincristine, prednisone). Eight patients underwent surgical treatment, three of them for compressive syndrome, followed by radiotherapy. The follow-up of patients with primary thyroid lymphoma revealed high disease aggressiveness and short survival, while complete remission was only occasionally recorded.