The hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis (EAA) is the paradigm of lung response to inhaled organic and inorganic. It is a relatively rare disease, constituting 2% of cases of interstitial lung diseases. The authors describe a case of a 60 years old man, with history of farming, who presented cough, sputum expectoration, fever, dyspnoea, chest pain, generalised swelling and haemoptysis. The study pointed to the initial diagnosis of pneumonia, but further study revealed that it was a case of chronic hypersensitivity pneumonitis. The authors present this case to emphasize the importance of history of exposure to any toxic substances, a lack of specificity of clinical manifestations, the need for invasive diagnostic methods and, sometimes, poor response to therapy