The use of ganciclovir (DHPG) in combination with interferon beta to prevent relapse of cytomegalovirus retinitis in patients with AIDS. While early clinical trials have shown that 30 mg/kg/week of DHPG is usually sufficient to delay or prevent relapse, neutropenia is a common dose-limiting problem in about 50 percent of patients. Since in vitro data have suggested that there is synergism between DHPG and interferon beta against cytomegalovirus, a reduced dose of DHPG in combination with a low dose of interferon beta may prevent relapse without causing neutropenia. If remission can be maintained with low-dose DHPG and interferon beta, maintenance therapy with a moderate dose of interferon beta alone will be evaluated in a subsequent protocol.