The utility of adjuvant chemotherapy after surgical resection for early-stage non-small cell lung cancer (NSCLC) is now well established. Although a number of randomized clinical trials have demonstrated the efficacy of platinum-based chemotherapy in the overall population treated, subset analysis, excepting Japanese studies, has uniformly shown the greatest efficacy for patients with stage II and III disease and the least benefit for patient with stage I disease. We review data regarding adjuvant therapy of stage I NSCLC from clinical trials performed in North America and Europe. Pertinent trials from Japan are discussed elsewhere in this issue.