In a series of 157 patients with acquired immunodeficiency syndrome (AIDS), 46 (29%) developed cytomegalovirus (CMV) retinitis. In five patients, CMV retinitis was the initial AIDS-defining opportunistic infection (11% of patients with CMV retinitis and 3% of patients with AIDS). Retinal detachments developed in seven patients (15%) and in four were present before the institution of ganciclovir therapy. Bilateral CMV retinitis was present in 35% of patients at presentation and subsequently developed in nine (60%) of 15 patients while not being treated with ganciclovir. Conversely, none of 18 patients with unilateral disease developed bilateral disease while receiving ganciclovir. Of patients treated with ganciclovir for their CMV retinitis, 81% had a response to the drug, and 61% achieved a complete response, resulting in a nonprogressive and inactive scar. Patients who achieved a complete response with ganciclovir had a significantly longer survival than those who did not, suggesting greater immune compromise in those patients who failed to respond to ganciclovir.