AIM: This experiment was performed to evalu at e the significance of the expression of different types of protein kinase C (PKC ) in lung squamous cell carcinoma induced by methylcholanthrene(MAC).METHODS: Lung squamous cell carcinoma in Wistar rats was induced with MAC for 12 weeks. The stage of the cancer development was determined histop athologically. Immunohistochemistry method was used to study the expression of different types of protein kinase C ?,?,?,? in lung squamous cell carcinoma. RESULTS: The level of expression of PKC ? in lung squamous cel l car cinoma was significantly higher than that in peripheral lung tissues and normal lung tissues (24.08%?2.93%,5.00%?2.10%,1.96%?0.29%,respectively. P