Inclusion Criteria

Patients must have:

• An underlying diagnosis of AIDS by CDC surveillance definition (group IV, category c-1 or subgroup D only).
• Colitis manifested clinically by diarrhea.
• Colon biopsy demonstrating a typical histologic picture of cytomegalovirus (CMV) disease.
• Cultures for CMV from blood and urine should be obtained within 1 week of study entry but need not be positive prior to entry. (A positive culture is needed for final inclusion in AN.)

Prior Medication:

Allowed:

• Topical acyclovir.

Exclusion Criteria

Co-existing Condition:

Patients with the following are excluded:

• History of chronic or acute liver disease.
• History of significant mental illness.
• Life expectancy < 1 month.
• Presence of any cause of colitis other than cytomegalovirus (CMV). (The following tests must be negative:
• Stool culture for enteric bacterial pathogens, stool exam for ova and parasites, stool exam for cryptosporidia, stool exam for AFB.) Colitis that is so severe that it would be against the patient's best interest to be treated with placebo for 2 weeks prior to being eligible to receive ganciclovir (DHPG) on a "compassionate" use basis. Patients with a colitis of this severity should be treated with DHPG on "compassionate" use basis.
• Presence of clinically significant extra-colonic active CMV disease of retina or visceral organs (which could progress during the no-treatment period).
• Presence of significant renal disease resulting in any decrement of creatinine clearance from normal.

Concurrent Medication:

Excluded:

• Any other investigational drug, whether or not as part of a formal clinical study.

Patients with the following are excluded:

• History of chronic or acute liver disease.
• History of significant mental illness.
• Life expectancy < 1 month.
• Presence of any cause of colitis other than cytomegalovirus (CMV). (The following tests must be negative:
• Stool culture for enteric bacterial pathogens, stool exam for ova and parasites, stool exam for cryptosporidia, stool exam for AFB.) Colitis that is so severe that it would be against the patient's best interest to be treated with placebo for 2 weeks prior to being eligible to receive ganciclovir (DHPG) on a "compassionate" use basis. Patients with a colitis of this severity should be treated with DHPG on "compassionate" use basis.
• Presence of clinically significant extra-colonic active CMV disease of retina or visceral organs (which could progress during the no-treatment period).
• Presence of significant renal disease resulting in any decrement of creatinine clearance from normal.

Prior Medication:

Excluded within 2 days of study entry:

• Nucleoside analogs.
• Excluded within 1 week of study entry:
• Antimetabolites or interferon.