Inclusion Criteria

Patients must:

• Be HIV seropositive and asymptomatic.
• Have normal neurologic exam as defined by the Micro Neuro-AIDS assessment.

Concurrent Medication

• Required: Prophylaxis for Pneumocystis carinii pneumonia (PCP). Aerosolized pentamidine is preferred but if not possible, Trimethoprim / sulfamethoxazole 1 DS tablet per day or Dapsone 50 - 100 mg per day is allowed.

Exclusion Criteria

• Active drug or alcohol abuse sufficient to prevent adequate compliance with study therapy in the investigator's opinion.

Co-existing Condition:

Patients with the following diseases or conditions are excluded:

• Hemophilia.
• Oral candida infection documented by morphology or by response to antifungal therapy within 2 years of study entry.
• Oral hairy leukoplakia at any time prior to study entry.
• Herpes zoster infection (including single dermatome infection) within 2 years of study entry.
• Active diarrhea as defined by 3 or more liquid stools per day.
• Temperature > 37.8 degrees C.
• Grade 1 impairment on two or more items (mild AIDS dementia complex) in the ACTG Micro Neuro-AIDS Assessment.
• Prior history of malignancy other than cutaneous basal cell carcinomas or cervical carcinoma in situ.

Patients with the following are excluded from entry:

• AIDS or AIDS-related complex defining symptoms.
• Significant, chronic underlying medical illnesses which would impair continuous participation in this 3-year clinical trial.
• Hemophilia.

Prior Medication: Excluded:

• Chemoprophylaxis for Pneumocystis carinii pneumonia (PCP).
• Other experimental medications.
• Excluded within 60 days of study entry:
• Antiretroviral drugs or immunomodulators (biologic response modifiers).
• Excluded within 120 days of study entry:
• Systemic corticosteroids.

Prior Treatment: Excluded within 3 months of study entry:

• Blood transfusion.