BACKGROUND Primary oculocerebral large cell malignant non-Hodgkin's lymphoma, formerly called ocular reticulum cell sarcoma, runs a uniformly fatal course. Once the central nervous system (CNS) is involved, survival without treatment is very limited. Although treatment does not substantially improve the long term survival, it provides short term improvement in these patients. METHODS The charts of all patients with ocular involvement of non-Hodgkin's lymphoma followed during the period 1984-93 were reviewed. The diagnosis of non-Hodgkin's lymphoma was made by different diagnostic approaches: CNS biopsy, anterior chamber tap, vitrectomy, haematology, and necropsy. RESULTS Eight patients had oculocerebral large cell and one had small cell non-Hodgkin's lymphoma. Five patients with pure ocular localisation had initially received steroid treatment for intermediate uveitis. First diagnosis was made on CNS biopsy in three, anterior chamber tap in one, vitreous aspirate in three, haematology in one, and necropsy in one case. CONCLUSIONS Ocular non-Hodgkin's lymphoma is a difficult diagnosis. Vitrectomy allows cytological diagnosis in most but not all cases. When no treatment is given, patients survive for only a few weeks once the CNS is involved. Although the disease is eventually fatal, treatment by means of radiotherapy, steroid administration, and vitrectomy can allow these patients to lead a normal professional and social life during the years between recurrences.