Edrecolomab is a murine IgG2a monoclonal antibody that recognizes the tumor-associated antigen Ep-CAM. Its antitumor effects are mediated through antibody-dependent cellular cytotoxicity, complement-mediated cytolysis, and the induction of an anti-idiotypic network. An initial study of 189 patients with resected stage III colorectal cancer showed that edrecolomab reduced the relative risk of mortality by 32% compared with observation alone (P < .01). Edrecolomab has now been investigated in two large phase III studies of patients with stage III colon cancer, either as a single agent or in combination with 5-FU-based chemotherapy. Preliminary safety data have shown that edrecolomab is well tolerated when used as monotherapy and adds little to chemotherapy-related side effects when used in combination. Edrecolomab is also being studied as monotherapy following resection of stage II colon cancer, and in combination with chemotherapy in patients with resected stage II or III rectal cancer. In conclusion, edrecolomab is a novel biological therapy for the adjuvant treatment of colorectal cancer. Completed and ongoing trials may support its use as monotherapy in stage II colon cancer or in combination with chemotherapy in stage III colon cancer and stage II/III rectal cancer.