OBJECTIVE Primary paranasal sinus lymphoma (PPSL) is a rare presentation of extranodal non-Hodgkin's lymphoma with a natural history distinct from other lymphomas. This study was to evaluate the clinical and pathologic characteristics, treatment outcomes and prognosis of PPSL. METHODS The records of 14 PPSL patients, treated at Cancer Center of Sun Yat-sen University from 1994 to 2006, were analyzed. RESULTS The primary involvement sites included the maxillary sinus (11 cases), ethmoid sinus (2 cases), and sphenoid sinus (1 case). All patients were at stage I-II (Ann Arbor system). According to the AJCC TNM staging system, most patients had advanced T3-T4 disease. Of the 14 patients, 12 had B-cell PPSL, 1 had T-cell PPSL, and 1 had unclassified PPSL. The most common type was diffuse large B-cell PPSL (6 cases, 42.9%). Two patients underwent total maxillectomy and 12 underwent local excision or biopsy. All patients received chemotherapy and 6 received radiotherapy after chemotherapy. Both 5-year overall and event-free survival rates were 78.6%, with a median survival of 59.5 months(range, 2-192 months). CONCLUSIONS PPSL is an uncommon presentation of lymphoma characterized by bulky local disease. Diffuse large B-cell lymphoma is the most common histologic type and the maxillary sinus is the most common original site of PPSL. A combined-modality approach with systemic chemotherapy and local-regional radiation is recommended for PPSL patients. The prognosis of PPSL is relatively good.