BACKGROUND: Lung cancer is the most frequently diagnosed cancer and leading cause among cancer mortality worldwide. An accurate classification is difficult in small biopsy specimens due to a variety of reasons. Therefore, there is an increasing need for additional diagnostic techniques such as immunohistochemistry. METHODS: This study was conducted on Endobronchial biopsies of One hundred and sixty patients were subjected to routine H & E and IHC staining. RESULTS: The patients were in age group of 25–75 years with a mean of 55.67 years with M: F ratio of 6.61:1. NSCLC constituted the major type, contributing to 83.1% of cases. Amongst, TTF–1 and napsin–A, the later had higher sensitivity (96.15%) as compared to TTF–1 (92.30%) for diagnosing adenocarcinoma. CONCLUSION: CK and p63 served as highly sensitive markers for diagnosis of squamous cell carcinoma and TTF–1 and napsin A for adenocarcinoma, forming an important diagnostic algorithm for subtyping of poorly differentiated NSCLC on small biopsies.