The combination of surgery with chemotherapy is the standard of care in stage II-IIIa surgical non small cell lung cancer. The survival benefit of chemotherapy corresponds to 4 to 8%. This benefit has been proved mainly by postoperative chemotherapy trials. When the positive results were published, most preoperative chemotherapy trials were closed. Nevertheless, the same survival benefit could be expected in preoperative chemotherapy trials. Furthermore preoperative chemotherapy has advantages: compliance of chemotherapy is excellent and tumor chemosensibility can be estimated. As the sequence of chemotherapy and surgery is not yet established, the French recommendations of the SOR (Standards, Options and Recommendations) suggest either pre or postoperative chemotherapy.