Pneumocystis carinii pneumonia (PCP) is a form of pneumonia that is the most common serious infection in persons with AIDS and the most common cause of death. With early recognition and the timely use of antibiotics, however, PCP is treatable. Several studies have shown that treatment variations for PCP appear to be widespread, as in-hospital mortality rates ranging from 10 to 60 percent have been reported. This Note documents the medical record abstraction and guidelines for PCP used in a study designed to evaluate quality of care for hospitalized AIDS patients with PCP who were treated in New York, Chicago, Los Angeles, and Miami. The major research questions to be answered in the study were: Among patients with AIDS-related PCP in these cities, are patients more likely to survive and receive better medical care when they are treated at hospitals that have had extensive experience with AIDS; are patients at hospitals that have low levels of experience with AIDS sicker at admission than patients at hospitals with high levels of experience with AIDS; and if differences in the quality of care exist among various hospitals, which patients are most affected — intravenous drug users, homosexual or bisexual men, or women who are sexual contacts of persons with AIDS? The purpose of the abstraction form and guidelines in this Note is to guide the collection of data from the medical records used in the four-city study.