To evaluate and compare the safety, tolerability, and effectiveness of long-term biweekly administration of 1 of 2 doses of aerosol pentamidine when used as a prophylactic agent in patients who have had multiple episodes of AIDS associated Pneumocystis carinii pneumonia (PCP).

Inclusion Criteria

Concurrent Medication:

Allowed:

• Zidovudine (AZT).

Patients must have:

• AIDS.
• Recovered from their most recent episode of Pneumocystis carinii pneumonia (PCP). Patients must be at least 2 weeks status post therapy for acute PCP.
• Adequate pulmonary function (vital capacity = or > 65 percent of predicted; forced expiratory volume, 1 s = or > 55 percent of total FEV; and corrected pulmonary diffusion capacity > 50 percent of predicted).
• Patients must be free of acute medical problems.

Exclusion Criteria

Co-existing Condition:

Patients with the following are excluded:

• AIDS-defining opportunistic infection prior to entry such as toxoplasmosis and cryptococcosis.
• Pulmonary Kaposi's sarcoma.
• Asthma poorly controlled by medication.
• Receiving active therapy for tuberculosis.

Concurrent Medication:

Excluded:

• Active therapy for tuberculosis.

Patients with the following are excluded:

• Requiring ongoing active therapy for an opportunistic infection at time of study entry.
• AIDS-defining opportunistic infection prior to study entry such as toxoplasmosis and cryptococcosis.
• Pulmonary Kaposi's sarcoma.
• Unwilling to sign informed consent.
• Asthma poorly controlled by medication.
• Unwilling to cooperate with study procedures.
• Receiving active therapy for tuberculosis.

Prior Medication:

Excluded within 30 days of study entry:

• Antiretrovirals (other than zidovudine (AZT)).
• Immunomodulating agents.
• Corticosteroids.

Prior Treatment:

Excluded within 7 days of study entry:

• Transfusion.
• Patient cannot be transfusion dependent (requiring blood transfusion more than once per month).

Active substance abuse.