Seven cases of non-Hodgkin lymphoma of the nasal cavities and paranasal sinuses are reported. All but one were primary lesions. Five of the 7 cases involved only the facial structures. Sites of involvement were the maxillary sinus (4 cases), the nasal fossae (2 cases), and one case in which lesions of both the ethmoid and sphenoid sinuses were associated with intracranial extension. CT studies showed sinus opacification and invasion of adjacent structures, but bone destruction was inconstant. Follow-up studies during treatment revealed rapid tumor regression with non specific images of mucosal hypertrophy.