Idiopathic acute eosinophilic pneumonia (IAEP) is characterized by febrile hypoxic respiratory failure with diffuse radiographic infiltrates and peripheral and pulmonary eosinophilia in a previously healthy child. Diagnosis is by exclusion, but promptness is imperative, as IAEP can lead to life-threatening acute lung injury and acute respiratory distress syndrome. Prognosis is usually good after steroid treatment with total recovery and absence of relapse in reported cases. We report a case of a previously healthy 14-year-old boy with this diagnosis who presented with acute hypoxia and characteristic radiographic and bronchoalveolar lavage findings. He had full recovery after corticosteroid treatment. This case report highlights the diagnostic approach to a patient with IAEP, an uncommon diagnosis, and one of the exclusions, in children.