Background: Hypersensitivity pneumonitis (HP) is a condition with an uncertain global incidence, and information on its diagnosis and management is limited. This study aimed to address these knowledge gaps. Methods: This study utilized customized claims data from the Health Insurance Review and Assessment Service (HIRA) in South Korea from January 2010, to December 2021. Patients with HP were identified based on the diagnosis code (International Classification of Diseases, 10th Revision, J67) between 2011 and 2020. Incident HP cases were defined as new HP claims, excluding those with claims in the previous year. The study examined various factors such as age, sex, comorbidities, diagnostic methods, and treatment patterns. Additionally, multivariate logistic regression analysis was performed to identify risk factors associated with treatment initiation. Results: A total of 8,678 HP incident cases were confirmed, with age- and sex-adjusted annual incidence rates ranging from 1.14/100,000 in 2020 to 2.16/100,000 in 2012. The mean age of patients with incident HP was 52 years, with a higher incidence observed among males. Additionally, the most common comorbidity was asthma. Bronchoscopy was performed on 16.9% of patients, and 25.4% of patients did not receive treatment within 1 year of diagnosis. Among those who received treatment, prednisone was the most used systemic steroid, and azathioprine was the most commonly used second-line immunosuppressant.Factors associated with treatment initiation included the female sex, having asthma or gastroesophageal reflux disease (GERD), and undergoing bronchoscopy. Conclusion This study provides valuable insights into the incidence, diagnosis, and treatment patterns of HP in South Korea using nationwide medical claims data.