Lung isolation during the lung lavage of children with pulmonary alveolar proteinosis (PAP) poses challenges to anaesthesiologists. There is no established technique in the management of lung lavage in children; each described technique has its own advantages and disadvantages. We described a patient (2.5-year-old) with PAP, who has undergone left lung lavage. While his lung was isolated by a Fogarty catheter, lavage was performed via a feeding tube, and the right lung was ventilated with a rigid bronchoscope. We suggested that the technique we used was safe and effective because it enabled direct visualisation of both bronchi entrances, allowing early recognition of any possible catheter dislocations at the bronchus of the lavaged lung, completely eliminating the risk of contralateral lung contamination. This case reports an alternative unilateral lung isolation and lavage technique that may be applicable to other paediatric patients with PAP.