Pulmonary alveolar proteinosis (PAP) is a rare disorder characterized by accumulation of lipoproteinaceous material within alveolar spaces, leading to respiratory failure. Whole lung lavage (WLL) is the current therapeutic option, but it may induce complete resolution of the disorder only in 30% of patients. Based on PAP pathophysiology, a few pilot studies dealing with administration of rGM-CSF (Sargramostim) to patients either s.c. or aerosolized have been performed, with hopeful results.Objectives. We designed an experimental, randomized by parallel groups, stratified according to previous treatment, open-label study looking at evaluation the superiority of the combination WLL/inhaled GM-CSF vs WLL alone in PAP patients. The study also includes a side, observational section. The primary efficacy objective is the total resolution of the pulmonary involvement in all treated patients. The study includes some secondary efficacy objectives as well: avoidance of disease recurrence, avoidance of respiratory infections, investigation of biomarkers predicting the disease outcome, effect of treatments on underlying pathophysiology of PAP.