The current mainstay of treatment for pulmonary alveolar proteinosis (PAP) is whole-lung lavage. Therapy with granulocyte-macrophage colony- stimulating factor is a possibility, although its long-term safety has not been determined. An alternative procedure is selected lobar lavage by fiberoptic bronchoscopy (FOB). We report here our experiences with lobar lavage by FOB in treating three patients with PAP. PAP was diagnosed in three patients (two men, one woman) who had dyspnea and hypoxemia after undergoing open-lung biopsy. The patients underwent lobar lavage by FOB under local anesthesia. The bronchoscope was wedged into a lobar bronchus. Approximately 2,000 mL warm normal saline solution was instilled via syringe in 50-mL aliquots through a fiberoptic bronchoscope. After undergoing multiple lobar lavages, two patients showed clinical, physiologic, and radiologic improvement. The third patient, who had more advanced disease, showed improvement only in oxygenation. The major complications were severe cough and hypoxemia during lavage. Our experience suggests that bronchoscopic lobar lavage is simple and safe, and may find application in patients in whom a whole-lung lavage with generalized anesthesia may be hazardous, and in patients with less advanced disease whose proteinaceous substances can be removed with a small volume of lavage fluid.