Idiopathic pulmonary alveolar proteinosis (PAP) is a rare disease due to impaired alveolar macrophage function caused by neutralising anti–granulocyte–macrophage colony–stimulating autoantibodies. A 57 years old female patient was admitted with complaints of non productive cough and dyspnoea at rest. There were bilaterally inspiratory fine crackles. The chest radiographs showed bilateral air–space consolidation. On thorax computed tomography; pre–carinal lymph nodes enlargement, ground glass opacities, septal thickening and crazy–paving appearance were determined. Bronchoalveolar lavage was performed and reported was PAP