Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD), consequence of an alveolar allergic reaction against various inhaled allergens occurring in susceptible individuals, manifesting as an acute or chronic granulomatous alveolar allergic process against inflammation of the lung parenchyma. The clinical presentation can mimic acute respiratory infections (in acute form) or an idiopathic ILD (in chronic form); the diagnosis of HP is difficult if the exposure to allergen is not suspected. We present the case of a male teenager, pigeon breeder, presenting with recurrent episodes of dyspnoea and fever, initially considered and treated as pneumonia. The diagnosis of HP was based on suggestive imaging changes, lymphocytic alveolitis at bronchoalveolar lavage with a low CD4/CD8 ratio and a thorough anamnesis for exposure and positive IgG serum precipitins against pigeon debris. The patient improved over a few months only by avoiding exposure to the incriminated allergen. ILDs in children and adolescents are considered rare diseases, with HP being one of the possible causes in older children and adolescents.