We reported a previously healthy 25-year-old female patient who developed hypersensitivity pneumonitis following repeated exposures to the smoke of mosquito coils. The patient presented with vague symptoms of cough and fever for 3 days. Diagnostic criteria proposed for clinical use in this case included history, exposure to a recognized antigen, physical examination, consistent radiographic images, bronchoalveolar lavage and lung biopsy. Much symptomatic relief and better radiographic response were noted after short-term use of oral corticosteroid and removal of the offending antigen.