A 43-year-old homosexual man was hospitalized in April 1988 because of acute epigastric pain. It was known that he had had a HIV infection for a year, and in April 1988 it was defined as stage Walter Reed I. Acute, exudative, nonspecific pancreatitis was diagnosed. Three weeks later cerebral symptoms (disturbances of consciousness), hypoacusis, and impaired vision developed. The ocular fundus displayed areas of edema and whitish clouding in the retina, first in the left eye and later also in the right. These were initially assumed to be anemic infarctions until the differential diagnosis of acute retinal necrosis with possible herpesvirus infection was made. On the basis of ophthalmoscopic findings cytomegalovirus retinitis appeared improbable. Serologic examinations showed increased levels of IgG antibody titers of cytomegalovirus and herpes simplex virus (both 1:20,000). Therapy with intravenous infusions of Acyclovir was instituted (1500 mg/d). After a few days the patient regained consciousness as well as his hearing and vision. There was complete resolution of the retinal exudates. This excellent therapeutic result of Acyclovir therapy confirmed the diagnosis of acute retinal necrosis syndrome, identified the cerebral symptoms as herpes encephalitis, and explained the entire disease process as the first opportunistic infection in HIV infection, i.e., by that time the patient had developed stage Walter Reed 6 (AIDS). Problems of differential diagnosis and the therapeutic schedule with Acyclovir are discussed.