All but the earliest cases of nonmetastatic gastric cancer represent a therapeutic challenge given the high propensity of these patients to develop locoregional and distant relapse. Neoadjuvant or adjuvant strategies that include chemoradiotherapy or chemotherapy have been associated with significant toxicity, but also improvement in patient survival. Technologic advances in the planning and delivery of radiotherapy (RT) have enabled significant progress in the accuracy and conformality of radiation treatment. Four-dimensional CT and image-guided RT improve the accuracy of radiation treatment. Three-dimensional RT and intensity-modulated RT allow increased conformality of radiation dose distribution, sparing of normal organs, and providing opportunity for dose escalation. Initial clinical experience with these technologies shows favorable tolerance and outcomes.