Background. Whole lung lavage is commonly performed for pulmonary alveolar proteinosis (PAP), however, segmental bronchoalveolar lavage is thought to be less useful. Patients and Method. We retrospectively evaluated the clinical features of 8 patients, who had been given a diagnosis of idiopathic PAP between 1995 and 2008. Results. All cases showed improvement during observation periods of from 1 to 13 years. One case improved naturally. Five cases, which had been treated with segmental bronchoalveolar lavage therapy, showed improvements in many aspects, such as symptoms, serum markers, and/or chest imaging findings. Conclusion. Our results suggest that not only whole lung lavage therapy, but also segmental bronchoalveolar lavage therapy may be a useful therapeutic method for idiopathic PAP, and it is important to determine the therapeutic approach, depending on the disease severity.