Non small cell lung cancer is the most frequent type of lung cancer and its prognosis is still very poor. Relapse is frequent and can be observed even in early stages of the disease, in spite of a surgical management with curative intent. This paper gives an overview of the main prognostic factors, the two most important of which remain the staging and tumor histology. These also determine the therapeutic strategy. Other factors of poor prognosis might also be useful for clinicians, particularly in their decision to refer patients for adjuvant therapies.