An AIDS patient with cytomegalovirus (CMV) retinitis was treated with ganciclovir (10 mg/kg) for four days followed by 5 mg/kg for 69 days. Clinically, CMV retinitis improved during therapy. Two weeks after induction of therapy, the patient became increasingly disoriented, and died 78 days after admission. Microscopically, a necrotizing encephalitis with characteristic cytomegalic cells with intranuclear inclusion bodies was observed. We conclude that ganciclovir therapy did not prevent development or progression of CMV encephalitis in the doses used.