Lung cancer is the leading cause of cancer deaths for people of both sexes worldwide. Early diagnosis of precancer lesions may be of crucial significance to lowering lung cancer mortality. The World Health Organization has defined three preneoplastic lesions of the bronchial epithelium: squamous dysplasia and carcinoma in situ, atypical adenomatous hyperplasia and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. These lesions are believed to progress to squamous cell carcinoma, adenocarcinoma and carcinoid tumors, respectively. Apart from WHO classification, two other lesions such as bronchiolization and bronchiolar columnar cell dysplasia (BCCD) can be observed and thought to be preneoplastic lesions leading to adenocarcinoma. In this review we summarize the data of morphological and cell cycle related proteins changes in both central and peripheral compartments of lung. Many molecular changes, which accompany the multistep process of the development of invasive types of cancer, may be observed thanks to the application of immunohistochemical markers. A deeper knowledge of molecular and genetic changes accompanying pre-cancer states may show new directions of early diagnostics of cancer development.