Plasmacytoma refers to malignant plasma cell tumor which consists of abnormal proliferation of plasma cells. It is classified as multiple myeloma, solitary medullary plasmacytoma and extramedullary plasmacytoma according to clinical and histological aspects of the tumor. Multiple myeloma is the most common plasmacytoma and the main feature is the infiltration of plasma cells into the bone marrow. Over 5% of plasma cell count among the nuclear cells in bone marrow biopsy allows to diagnosis multiple myeloma. This involves multiple organs and extramedullary sites include spleen, liver, lymph nodes and kidney. Involvement of paranasal sinus is rare but it can cause visual disturbance followed by pressure on optic nerve in sphenoid sinus. Recently, we experienced a case of multiple myeloma which was present in both nasal cavities and paranasal sinuses treated with chemotherapy and radiotherapy followed by autologous bone marrow transplantation and report with literature review.