Objective: To investigate for the expression of immunohistochemical markers of lung carcinoma types according to WHO histological classification 2004. Material and method: 115 cases of lung carcinomas were histologically classified according to WHO 2004, and stained immunohistochemical markers: p53, p63, CK5/6, CK7, Ki67, TTF-1, NSE for the lung carcinoma types. Results: Histologically, adenocarcinomas were identified in 49.3 percent, squamous cell carcinomas in 31.2 percent, and adeno-squamous carcinomas in 15.6 percent. CK7 was expressed in 97.4 percent of the adenocarcinomas, 83.3 percent of the adeno-squamous carcinomas, 41.6 percent of squamous cell carcinomas. Forty-one-point-six percent of squamous cell carcinoma were positive for CK5/6, the other types were negative for CK5/6. Adeno-squamous carcinomas had a highest positive rate for Ki-67 (75 percent), followed by the squamous cell carcinomas (66.6 percent), and adenocarcinomas (36.8 percent). Seventypoint-eight percent of squamous cell carcinomas, 25 percent of adeno-squamous carcinomas and 18.8 percent of adenocarcinomas were positive for p63. The percentage of TTF-1 positivity of adenocarcinoma was higher than squamous cell carcinoma (53.8 percent versus 46.1 percent). Fifty percent of squamous cell carcinomas, adenocarcinomas and adeno-squamous carcinomas were positive for p53. All the case of small cell carcinomas were negative for CK7 while 89.5 percent of them were positive for Ki-67, 50 percent for p53 and 38.4 percent cases for NSE. Conclusion: Adenocarcinoma was the most common type in lung cancer. CK5/6 and p63 is more specific for squamous cell carcinomas of the lung while CK7 was more specific with adenocarcinoma . Adeno-squamous cell carcinoma had a high rate of positivity for Ki67. p53 was positive equally among the adenocarcinoma, squamous cell carcinoma and adeno-squamous carcinoma. All of the small cell carcinomas (SCC) were negative for CK7, while highly positive for Ki67.