Abstract: Primary lymphoma of thyroid is a rare entity among thyroid diseases which constitute only 5% of all thyroid malignancies. Primary thyroid lymphomas are almost always associated with chronic lymphocytic thyroiditis. Most of them are B-cell origin Non-Hodgkin lymphomas, most common subtype is diffuse large B-cell lymphoma (DLBCL) followed by Mucosa associated lymphoid tissue (MALT) lymphoma. Treatment and outcome of primary thyroid lymphoma depends on histological subtype and stage of the disease. Here we report two cases of primary thyroid lymphoma of B-cell origin diffuse large B-cell lymphoma and MALT lymphoma. First case is a 48 years old lady who presented with diffuse enlargement of thyroid with retrosternal extension complained of breathlessness and chest discomfort, which was confirmed by MRI scan. FNAC was Lymphocytic thyroiditis-Bethesda Category II. She underwent total thyroidectomy due to compression symptoms and histopathological diagnosis was diffuse large B cell lymphoma after immunohistochemistry. Second case is a 72 years old man who presented with a huge thyroid mass with rapid increase in size over one month duration, associated with hoarseness of voice and difficulty in swallowing. CT scan revealed grossly enlarged thyroid extending into prevertebral area causing compression of esophagus. Total thyroidectomy was done, final diagnosis of which was Non-Hodgkin lymphoma, possibly MALT lymphoma with associated diffuse high grade areas in a background of lymphocytic thyroiditis.