Adjuvant chemotherapy using a cisplatin-based regimen is currently recommended for patients with stage II and III non–small cell lung cancer (NSCLC) after complete tumor resection and may be considered for patients with stage IB NSCLC. Although adjuvant chemotherapy after complete resection of localized NSCLC is associated with an absolute survival advantage of approximately 5% at 5 years, there is still a relatively high risk of relapse even for early-stage NSCLC. Efforts are ongoing to identify new treatments in the adjuvant setting and to select patients for individualized treatment based on biomarkers.