The overall goal of this project is to design and implement clinical studies of the treatment of Pneumocystis carinii pneumonia in patients with HIV infection and the acquired immunodeficiency syndrome (AIDS). In the first part of the project a generic protocol will be developed which can be used to conduct prospective, controlled, double-blind trials of drugs in the therapy of first episodes of PCP. These trials will be cooperative studies involving multiple institutions. The protocol will involve comparison of the efficacy and toxicity of a new drug with a standard administered to hospitalized patients for 14-21 days. Alpha-Difluoromethyl-ornithine (DFMO) and pentamidine isethionate will serve as the new and standard drugs, respectively, in the first trial. Fiberoptic bronchoscopy with broncho-alveolar lavage will be performed at the beginning and end of therapy, and analysis will be performed on PC organism number and viability. The treatment protocol is designed as a sequential clinical trial with data analysis being done every two months. A Performance and Safety Monitoring Committee will be established to monitor the study. Data obtained from these studies will lead to a more organized and efficient approach to the evaluation of new anti-PCP drugs, as well as a more accurate assessment of the effects of these agents on the organism.