Interstitial lung disease (ILD) is rare and encompasses a heterogeneous group of diseases, and is even rarer in children than in adults. ILDs compromise more than 100 different entities, including pulmonary alveolar proteinosis (PAP). There are many causes of PAP in children, including surfactant protein gene mutations (SFTPB, SFTPC, ABCA3, TTF-1), GMCSF receptor mutations and antigranulocyte-macrophage colony-stimulating factor autoantibodies. We report a case of a 13-year-old Chilean girl who presented with an 8-month history of progressive exercise intolerance, fatigability and diminished school performance. Physical examination revealed resting tachypnoea, a few basal bilateral inspiratory crackles, and hypoxaemia on minimal exertion. Clinical suspicion and evaluation, including international collaboration, led to the diagnosis of autoimmune PAP and specific therapy for the condition. Copyright 2014 BMJ Publishing Group. All rights reserved.