Granulomatous lung disorders are a heterogeneous collection of diseases that include both infectious and noninfectious conditions (e.g. sarcoidosis). Because of the heterogeneity, the diagnostic approach is varied and challenging. This chapter aims to strategise and simplify the diagnostic approach to granulomatous lung disorders. The differential diagnosis of granulomatous conditions is constructed based on the characteristics of granulomas, the presence and type of necrosis, their morphology and their dominant site of occurrence in relation to the structures of the lung. Granulomas are sometimes unexpectedly discovered on lung biopsy. This chapter also discusses the thoracic conditions that need to be ruled out upon obtaining a granulomatous biopsy. The discussion also highlights sarcoidosis, a common granulomatous disease that can affect almost any organ. The diagnostic basis of sarcoidosis, the sites to screen while looking for a ‘second’ organ involvement that is necessary to the diagnosis, the value of the serum angiotensin converting enzyme and the Tuberculin test in the diagnosis of sarcoidosis are also discussed.