Pulmonary lesions were seen in nine patients with diseases endemic to the tropics. Five patients with Plasmodium falciparum malaria and one patient each with leptospirosis, scrub typhus, bubonic plague, and typhoid fever developed pulmonary infiltrates during the course of their infection. In the cases of malaria, scrub typhus and leptospirosis, bacteriologic and viral studies were negative and the pneumonias were presumed to be a manifestation of the specific illness. Pasteurella pestis (Yersinia pestis) was isolated from the sputum and blood of one patient with bubonic plague who had secondary pneumonic complications. Salmonella typhosa was isolated from the blood cultures of another patient with typhoid fever who developed pulmonary infiltrates. In each of the above cases, resolution of the pulmonary lesions coincided with improvement of clinical symptoms.