The etiology of pulmonary disease In AIDS patients in our setting Is presented, comparing two staining techniques; 36 patients with pulmonary disease were studied (31%) of the 116 reported with AIDS at the epidemiology department of the local heath service In the Department of Antioquia between May 1990 and May 1992. AII of them were studied with bronchoalveolar lavage and staining with modified methenamine silver and calcofluor white stain. It was found that P. carinii is responsible for 28% of cases of pulmonary disease In AIDS patients. No characteristic clinical presentation of pulmonary disease by P. carinii was found that helps to differentiate it from that caused by other etiologic agents. Staining with calco fluor white was as reliable as that with modified methenamine silver stain; it is simpler, easier to Interpret, and has a lower cost, which makes it the most suitable staining technique in our patients.