Background: Gastric cancer is a condition with a high medical need. Even after R0 resection the rate of peritoneal and other distant site recurrences is high. Novel therapeutic approaches include trifunctional antibodies (trAb) that recruit and activate different types of immune effector cells at the tumour site. The trAb catumaxomab has dual antigen specificity for epithelial cell adhesion molecule and CD3 and binds to Fcγ-receptor-positive accessory cells. Intraperitoneal administration of catumaxomab in patients with malignant ascites due to epithelial cancer significantly increased puncture-free survival. Objective: To review the mode of action of catumaxomab and describe clinical data regarding the emerging role of catumaxomab in the treatment of patients with gastric cancer. A summary of completed and ongoing clinical trials including patients with gastric cancer is given. Conclusion: Catumaxomab is a promising approach in the treatment of patients with gastric cancer.