Background. Transbronchial lung biopsy (TBLB) is commonly performed for confirming the tissue diagnosis of diffuse parenchymal lung diseases (DPLDs). There is an urgent need to establish guidelines for interpretation of TBLB in order to improve its diagnostic utility. Methods. We retrospectively studied 916 consecutive patients (494 males; mean age 49 years) who underwent TBLB over a 5-year period (July 2005 to July 2010) at Vallabhbhai Patel Chest Institute. Results. In 615 (67.1%) procedures, material obtained during TBLB was adequate for histopathology interpretation. Pathological features evaluated in each case were: alveolar architecture, inflammatory infiltrate, interstitial fibrosis, atypical cells, pigment deposition, honey-comb change and fibroblast foci. The cases were categorised on the basis of histopathology into six patterns: (1) adequate biopsy without a specific diagnostic abnormality (n=137, 22.3%); (2) acute pneumonitis (n=29, 4.7%); (3) neoplasia (n=109, 17.7%); (4) chronic interstitial inflammation with or without fibrosis (n=138, 22.4%); (5) granulomatous inflammation, (n=186, 30.2%); and (6) other specific causes (n=16, 2.6%). Definitive diagnosis could be made after correlation of TBLB histopathology with clinical and radiological features in 55.3% cases. Conclusions. TBLB appears to be an important diagnostic tool for the diagnosis of DPLDs. The use of a pattern-based approach to TBLB adds to its diagnostic yield and can be helpful in cases where open lung biopsy is not available.