Cytomegalovirus (CMV) infection of the retina is the commonest potentially blinding ocular manifestation of AIDS. Recently the acyclic nucleoside dihydroxypropoxymethyl guanine (DHPG, ganciclovir) has become available to treat sight-threatening CMV retinopathy. This paper reports the clinical features and results of ganciclovir therapy in 48 patients seen over a four-year period. Seven patients were excluded from the study due to inadequate follow-up, leaving 41 patients as the study group. All patients responded clinically to this therapy. Patients were treated initially with high-dose ganciclovir (10 mg/kg/day) and then continued on lower dose treatment (5 mg/kg/day) indefinitely. Significant bone marrow toxicity developed in 12 patients (29.3%) requiring temporary cessation of therapy. Patients treated with ganciclovir retained vision and had increased survival times when compared to untreated patients. A poor visual outcome occurred when there was involvement of the macula or optic nerve head at presentation or when there was an interruption of ganciclovir therapy.