Pulmonary alveolar proteinosis (PAP) is a rare disease and its prognosis can be improved by whole lung lavage (WLL). Herein, we present three cases with idiopathic PAP treated successfully with either single or double WLL in the same setting. All three of them presented with exertional dyspnoea with radiographic findings of pulmonary infiltrates. They showed a marked clinical and physiologic improvement post WLL. Two of them were in remission. These three cases were diagnosed using different lung biopsy modalities, including video-assisted thoracoscopic lung biopsy, computed tomography-guided percutaneous transthoracic tru-cut needle lung biopsy, and transbronchial forceps lung biopsy (TBLB), respectively. The current cases have shown that TBLB may provide adequate diagnostic yield, and the invasive surgical lung biopsy may not be necessary to achieve a definitive diagnosis.