Whole lung lavage (WLL) is the standard treatment for pulmonary alveolar proteinosis (PAP). This study aimed to provide data about the kinetics of the protein wash-out, to identify factors influencing the protein concentration in the recovered fluid and to assess the efficacy of a modified lavage technique. Samples of 180 WLLs from 42 adult PAP patients were collected. 110 WLLs were performed according to the classical technique. In 70 WLLs, repeated manual ventilation was applied during the procedure. Spectrophotometry was used to measure the protein concentration in the recovered fluid. The initial protein concentration in the recovered fluid was 460 mg · dL(-1), the final concentration was 26 mg · dL(-1) and the total amount of removed proteins during a lavage was 17.5 g. A history of dust exposure was associated with a higher residual protein concentration in the recovered fluid (p=0.000013). The amount of removed proteins correlated inversely with the diffusing capacity of the lung for carbon monoxide (p=0.001) and oxygen tension (p=0.004). The modified technique removed a greater amount of proteins than the classical technique and prolonged the time to relapse (p=0.011). Exposure to dust seems to influence the kinetics of the protein wash-out. Applying manual ventilation during the procedure can enhance the efficacy of WLL.