Pulmonary alveolar proteinosis is characterized by an amorphous lipoproteinaceous material filling the acini of the lung, resulting in hypoxemia. At present, the most effective treatment for alveolar proteinosis is lung lavage. Here, we report the first case in Taiwan treated with this method. A 38-year-old male with a 6-month history of cough and increasing breathlessness was transferred from another hospital. On admission, his arterial oxygen tension was 51 mmHg when breathing room air. Chest X-ray films showed diffuse infiltration of both lung fields. Transbronchoscopic lung biopsy was consistent with alveolar proteinosis, therefore the patient was submitted to pulmonary lavage. Under general anesthesia, the patient was intubated with a left-sided double lumen endotracheal tube, and lavage of the right lung was repeated with 0.9% saline until the washing became clear. At the end of the procedure, the patient was extubated after making strong respiratory efforts. Several days later, the left lung was lavaged using the same technique. The mechanical washing of amorphous material from alveoli by pulmonary lavage is of great benefit in relieving hypoxemia. Judicious use of lung lavage is effective and safe for patient with alveolar proteinosis.