Background/Aims: To describe the clinical features, imaging, histologic spectrum, treatment and prognosis of patients with malignant orbital lymphoproliferative disorders extending from the paranasal sinuses. Methods: Patients were culled from the University of British Columbia Orbit Clinic (1977-2004) and their clinical charts, imaging and pathology specimens reviewed. Results: The study included 6 patients with non-Hodgkin's lymphoma (NHL) and 5 multiple myeloma (MM). Orbital symptoms at presentation were periorbital swelling, diplopia, proptosis and pain. Major clinical findings were globe displacement, abnormal ocular movements, periorbital fullness, fifth nerve hypoesthesia and inflammatory signs. Imaging showed a soft tissue mass in one or more sinuses invading the orbit. Three NHL patients were still alive at last follow-up with one patient lost to follow-up. Two NHL patients and all MM died. Conclusion: Presenting symptoms of malignant orbital lymphoproliferative disorders extending from the paranasal sinuses include mass effect occasionally with infiltrative and inflammatory characteristics accompanied by symptoms of sinus disease. On imaging, a soft tissue mass in the sinuses and orbit with bone destruction is commonly seen. Biopsy is essential for conclusive diagnosis. Treatment should be initiated promptly as local symptoms are frequently relieved and survival is possible, especially in cases of NHL.