Gastric cancer is still a major health problem and a leading cause of cancer mortality despite a worldwide decline in incidence. Surgical resection with curative potential is the only treatment modality of scientific proven effectiveness. Many phase III trials of adjuvant therapy have been conducted, however, postoperative treatment modalities have not proven to be superior to pos-surgical observation alone. Therefore, at present the routine use of adjuvant therapy should be regarded as an investigational approach. Improved clinical trial designs with standardized surgical techniques and the incorporation of newer active drugs are needed.