Three patients complained of deteriorating vision 16, 20 and 29 weeks following bone marrow transplantation (BMT) while receiving cyclosporine (CsA). Opthalmic examination revealed a marked microvascular retinopathy with multiple cotton-wool spots, macular stars and retinal oedema. These appearances could not be accounted for by the mild to moderate hypertension in two cases, the third patient being normotensive. Two of the patients had received total body irradiation (TBI) and cyclophosphamide (CY) as conditioning therapy for BMT as well as previous cranial irradiation for acute lymphoblastic leukaemia; one case with chronic myeloid leukaemia was conditioned with busulphan and CY. Withdrawal of CsA in two patients and reduction of dose in the third led to complete resolution of retinopathy and restoration of visual function. Previous reports have documented ischaemic fundus lesion in BMT recipients treated with CsA and TBI. Our findings suggest that CsA in association with busulphan can produce a similar retinopathy.