Studies of adjuvant chemotherapy for non-small cell lung cancer (NSCLC) did not provide a consistent disease-free survival or overall survival benefit in the 1980s and early 1990s. However, recently reported studies have changed the practice of NSCLC treatment, for which adjuvant chemotherapy is now considered the standard of care. This review outlines the issues that may have limited the detection of beneficial effects of adjuvant chemotherapy in early trials and provides detailed analysis of the results of recently published trials of adjuvant chemotherapy for NSCLC.