Between February 1996 and October 1997, 249 cancer patients with chest radiographic findings suggestive of pneumonia were prospectively evaluated. All patients underwent bronchoscopy, and the BAL fluid was sent for microscopy, cytology, and bacterial, viral, and fungal cultures. Information was obtained on all patients as to their age, gender, race, underlying diagnosis, and history of bone marrow transplant. In addition, further information pertaining to clinical manifestations of the infection, such as fever, cough, hemoptysis, dyspnea, pleuritic chest pain, sinus symptoms, and prior lung disease, was obtained. Clinical signs of the infection, particularly pleuritic friction rub, rales, or rhonchi, were assessed. In addition, the risk factors for the infection, such as use of steroids, duration of neutropenia, and prior chemotherapy were also determined. Information was also obtained on the radiologic and laboratory findings, such as CT of the chest, as well as the chest radiograph and sinus radiographs. Histopathologic findings obtained on the BAL, transbronchial, fine-needle, or open-lung biopsy, and autopsy if available were also documented. The treatment that the patient received, in terms of antibiotics and antifungal therapy, was also determined on all patients. Patients were followed up prospectively until death or discharge.