Hypersensitivity pneumonitis (HP) is a rarely diagnosed interstitial lung disease with variable manifestations. It results from repeated inhalation of certain antigens, e.g. mold, avian antigen, etc. in susceptible patients. The diagnosis is made by exposure history, relevant clinical presentation, and specific radiologic features. It is treated by avoidance of triggers and use of corticosteroids. We report a 7.5-year girl with HP. She was admitted for cough and severe respiratory distress. Key Words: Hypersensitivity pneumonitis, Antigen, Allergy, Child.