Primary thyroid lymphoma is a rare malignancy, representing 2-8% of all thyroid malignancies and 1-2% of all extranodal lymphomas. The majority of cases concern non-Hodgkin's lymphoma of B cell origin, following by Hodgkin's disease, T cell lymphomas and rarely marginal zone B-cell mucosa-associated lymphoid tissue (MALT) lymphomas. MALT lymphomas have been associated with long-standing autoimmune Hashimoto's thyroiditis. We present the case of a 44-years-old woman with thyroid MALT lymphoma in the background of multinodular goiter of autoimmune origin.