We reviewed the records and biopsy specimens of 38 patients with clinically similar orbital lymphoproliferative and low-grade inflammatory lesions referred to one ophthalmologist at the University of British Columbia between 1977 and 1984. Twenty-six patients had lymphoproliferative lesions, the main feature being a densely cellular population of small lymphocytes. This group was further divided into reactive lymphoid hyperplasia, malignant lymphoma, Hodgkin's disease and atypical lymphoid hyperplasia. Symptoms and signs were similar within the subgroups. The mean length of follow-up was 3.7 years. Of the 26 patients 14 had extraorbital lymphoproliferative disease, 9 had orbital recurrences and 2 died of widespread disease. Twelve patients had inflammatory lesions with distinctly different histologic features from those of the lymphoproliferative group. Symptoms and signs were similar to those in the latter group. The mean length of follow-up was 2.1 years. Four of the 12 had orbital recurrences; none had extraorbital disease or died of their disease. We feel that orbital lymphoproliferative lesions can easily be separated from clinically similar low-grade inflammatory lesions histologically and that they should be staged and followed like small lymphocytic lymphomas. Guidelines are given for handling these specimens in the laboratory.