Gastric cancer has a poor prognosis. The majority of patients will relapse after definitive surgery, and 5-year survival after surgery remains poor. The role of adjuvant therapy in gastric cancer has been controversial given the lack of significant survival benefit in many randomized studies so far. The results of a large North American study (Gastrointestinal Cancer Intergroup Trial INT 0116) reported that postoperative chemoradiotherapy conferred a survival advantage compared with surgery alone, which has led to the regimen being adopted as a new standard of care. However, controversies still remain regarding surgical technique, the place of more effective and less toxic chemotherapy regimens, and the use of more modern radiation planning techniques to improve treatment delivery and outcome in the adjuvant and neoadjuvant setting. This article reviews the current status of the adjuvant treatment for gastric cancer including discussion on the research directions aimed at optimizing treatment efficacy. Issues such as the identification of patients who are more likely to benefit from adjuvant therapy are also addressed. Further clinical trials are needed to move towards better consensus and standardization of care.