Pulmonary alveolar proteinosis is such an extremely rare disease in Korea, that only a few cases have been reported. Meanwhile five cases were experienced at Seoul National University Hospital over ten years since 1987. We summarized the clinical characteristics and courses of them. Seven cases reported in the literature were included to add data about clinical characteristics and courses although only a few case reports mentioned patient's course. Middle aged male patients were mainly affected. No association with particular environmental or occupational exposure was identified. Dyspnea on exertion was the main symptom. Bilateral crackles were consistent, and bilateral parahilar hazy infiltrations on plain chest radiograph and ground glass opacity on high-resolution CT were characteristic. Superimposed infection was not identified in any patient at the time of diagnosis. Decreased diffusing capacity and hypoxia were present in almost every case. Whole lung lavage proved to be an effective therapeutic measure. The response to treatment was good. Long-term course of the disease, e.g. recurrence rate, is not yet known.