KRAS mutations occur in 30% of patients with non-small cell lung cancer, especially adenocarcinoma. For long time KRAS mutation has been related with poor prognosis and poor response to chemotherapy. Recent data however show that this is both not true. It seems that response, progression free survival and overall survival is similar in KRAS mutated. Until now no specific targeted therapy is available for KRAS mutated NSCLC patients. Optimization of treatment in advanced NSCLC patients with a KRAS mutation could also be achieved by selecting the best available chemotherapy treatment.