Between January 1, 1989, and December 31, 1991, pulmonary Kaposi's sarcoma (KS) was diagnosed in 25 patients (23 men and 2 women) with acquired immune deficiency syndrome (AIDS) in our institution. Cutaneous KS was also present in 24 cases. All patients underwent flexible bronchoscopy (FFB). The simple visualization of typical KS lesions distributed along the tracheobronchial tree was the diagnostic method exclusively in 20 (80.0%) patients. Direct biopsy of visible lesions was positive in 36.4% (4 of 11) cases. Bronchoscopic lung biopsy was performed in six patients, positive for KS in one (16.7%). Abnormal bleeding was not noted. Overall, FFB was diagnostic for pulmonary KS in 24 (96.0%) patients. Surgical lung biopsy was performed in one case with negative findings for KS on FFB. Associated simultaneous pulmonary diseases were present in nine (36.0%) cases: tuberculosis in three,Pneumocystis cariniipneumonia in three, atypical mycobacterial disease in two, and bacterial pneumonia in one. Despite chemotherapy, the 6-month survival rate was only 31.8%