Inclusion Criteria

Concurrent Medication:

Allowed:

• Aerosolized pentamidine for Pneumocystis carinii pneumonia (PCP) prophylaxis.
• Oral antibiotics if patient is hematologically stable on that regimen for at least 30 days prior to study entry.
• Therapy with vancomycin.
• Drug therapy for Kaposi's sarcoma if patient is hematologically stable for at least 30 days prior to study entry.
• Initiate or resume zidovudine (AZT) in 2nd week of foscarnet maintenance therapy at dose of 100 or 200 mg q4h at investigator's discretion.
• Initiate or continue erythropoietin therapy via the treatment IND mechanism.
• Initiate or continue therapy with investigational triazoles for disseminated fungal infections. Caution should be used in concurrent use of foscarnet and ciprofloxacin, as such use has appeared to exacerbate renal failure in one patient.

Prior Medication:

Allowed:

• Oral antibiotics if patient is hematologically stable on that regimen for at least 30 days prior to study entry.
• Drug therapy for Kaposi's sarcoma if patient is hematologically stable for at least 30 days prior to study entry.

Exclusion Criteria

Co-existing Condition:

Patients with the following are excluded:

• Corneal, lens, or vitreous opacification that precludes examination of the fundi.
• Clinically significant pulmonary or neurologic impairment, including intubation or coma.
• Karnofsky performance status = or < 50.

Concurrent Medication:

Excluded:

• Immunomodulators.
• Biologic response modifiers.
• Investigational agents (other than erythropoietin and investigational triazoles).
• Ganciclovir.
• Didanosine (ddI).
• Systemic acyclovir.
• CMV hyperimmune serum / globulin.
• Interferons.
• Nephrotoxic agents including aminoglycosides, amphotericin B, parenteral pentamidine.
• Caution should be used in the concurrent use of foscarnet and ciprofloxacin, as such use has appeared to exacerbate renal failure in one patient.

Patients with the following are excluded:

• Corneal, lens, or vitreous opacification that precludes examination of the fundi.
• Clinically significant pulmonary or neurologic impairment, including intubation or coma.
• Unwilling or unable to suspend zidovudine treatment until 2nd week of foscarnet maintenance therapy.

Prior Medication:

Excluded:

• Foscarnet for cytomegalovirus retinitis.
• Systemic acyclovir.
• Immunomodulators.
• Biologic response modifiers.
• Investigational agents (other than erythropoietin and investigational triazoles).

AIDS patients with active cytomegalovirus (CMV) retinitis who cannot be treated with ganciclovir. At least one pending CMV culture from both blood (buffy-coat) and urine must be obtained prior to study entry. Patients must be able to give informed consent. Patients with a history of a seizure disorder or central nervous system mass lesion will be included.