Completely resected non small-cell lung cancer (NSCLC) patients frequently experience local or systemic relapse of their disease. In order to decrease the risk of relapse, postoperative (adjuvant) treatments have been studied. To date, the several published or reported randomised trials on postoperative chemotherapy show that adjuvant chemotherapy should be regarded as a standard of care for stage II and IIIA completely resected NSCLC. On the other hand, available data suggest that adjuvant radiotherapy has a detrimental effect on survival of completely resected stage I and II NSCLC patients. The relevance of adjuvant radiotherapy for stage IIIAN2 NSCLC patients has not been demonstrated to date. Choice of drugs, combination with targeted therapies, optimal treatment schedules, the management of stage I NSCLC patients and individually-based adjuvant therapeutic strategies are currently being evaluated in clinical trials in which the participation of all investigators is essential.