Idiopathic pulmonary fibrosis (IPF) is a progressive fibrosing interstitial lung disease characterized by worsening lung function and dyspnea. The prognosis of IPF patients is poor, as median survival is approximately 3 years. However, recently developed IPF-specific therapies have shown improved efficacies in terms of reducing lung function decline and mortality. Therefore, the early recognition and accurate diagnosis of IPF are crucial. In 2018, new guidelines for the diagnosis of IPF were published by the Fleischner Society and by the American Thoracic Society/European Respiratory Society/Japanese Respiratory Society/Latin American Thoracic Society (ATS/ERS/JRS/ALAT). Both guidelines emphasize the need for a thorough history taking and physical examination to exclude an alternative diagnosis, such as exposure-related or connective tissue disease. The most informative initial examination is high-resolution computed tomography, the results of which can indicate the need for bronchoalveolar lavage or surgical lung biopsy, based on a multidisciplinary discussion of the findings and the patient’s clinical condition. A multidisciplinary discussion of the clinico-radiologic-pathologic findings is currently the gold standard in the diagnoisis of IPF and will allow the more effective and timely treatment of these patients. (Korean J Med 2019;94:173-181)