Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-specific death in the USA and Europe. Over the last two decades, the pathogenetic mechanisms and the molecular alterations of NSCLC have been investigated more intensively, a number of potential therapeutic targets have been identified and new agents against specific molecular targets have been introduced in the treatment of NSCLC. Acquired abnormalities in the genes encoding RAS, p53, KRAS, EGFR and ALK, are particularly important in this field. Whenever targetable mutations are not found, the research of other genetic abnormalities can be useful to personalize chemotherapy. The attention has been focused, in particular, on the endonuclease excision repair cross-complementing1 and BRCA1 status. The use of antimetabolite drugs and the level of expression of their cellular targets seem to be correlated and influence the clinical efficacy of those agents. This review will focus on the role of predictive biomarkers for the treatment of non-small cell lung cancer.