Since the original report by Rosen, Castleman, and Liebow1in June, 1958, of the then-new entity of pulmonary alveolar proteinosis, many additional cases have been reported.2-19The name is now well established and a fairly characteristic clinical pattern is beginning to emerge. Despite the wide geographical distribution of this disease and the increasing number of cases, the etiology remains unknown, and the treatment, where it has been attempted, has been entirely empirical. None of the cases reported has shown dramatic response to any of the treatments employed. A case of pulmonary alveolar proteinosis, previously proven by lung biopsy has been treated with streptokinase-streptodornase enzyme aerosol, with a marked concomitant change in findings. Since this case has been previously reported,19only the details relevant to the treatment are included in this report. Report of Case A 32-year-old white man, screw-machine operator, was found to have pulmonary alveolar proteinosis