目的ＭＧ抗原（ＭＧＡｇ）是一组新的胃癌相关抗原，本研究评价其临床应用价值及意义．方法应用胃癌单克隆抗体建立的一步法免疫放射分析法（ＩＲＭＡ）检测了４０例胃癌患者，３３例慢性良性胃病患者和２０例正常人血清中的ＭＧＡｇ．结果胃癌患者血清ＭＧＡｇ含量及阳性率明显高于正常人及良性胃病患者（Ｐ＜００１）；Ⅲ～Ⅳ期患者ＭＧＡｇ显著高于Ⅰ～Ⅱ期患者（Ｐ＜００５）；有远处和（或）区域淋巴结转移患者ＭＧＡｇ明显高于未有转移患者；贲门癌患者ＭＧＡｇ较胃窦、体癌高，但无统计学意义（Ｐ＞００５）．对１０例行胃癌切除术的ＭＧＡｇ阳性患者，术后１０ｄ～１４ｄ检测血清ＭＧＡｇ明显下降（Ｐ＜００１）．结论检测血清ＭＧＡｇ对胃癌诊断、判断胃癌病情、观察手术疗效及预后判断具有较高的临床价值． Objective MG antigen (MGAg) is a new group of gastric cancer-associated antigens. This study evaluated its clinical application value and significance. Methods One-step immunoradiometric assay (IRMA) established with monoclonal antibody against gastric cancer was used to detect MGAg in 40 patients with gastric cancer, 33 patients with chronic benign gastropathy and 20 normal controls. Results The serum MGAg content and positive rate in gastric cancer patients were significantly higher than those in normal and benign gastropathy patients (P<001). The MGAg levels in patients with stage III-IV were significantly higher than those in stage I-II patients (P<005); MGAg in patients with regional and/or regional lymph node metastases was significantly higher than those without metastasis; MGAg in patients with cardiac cancer was higher than that in antral and carcinoid tumors, but it was not statistically significant (P>005). For 10 cases of MGAg positive patients who underwent gastric cancer resection, serum MGAg was significantly decreased after 10 days to 14 days (P<001). [Conclusion] Detection of serum MGAg is of high clinical value in the diagnosis of gastric cancer, judging the condition of gastric cancer, observing the curative effect and judging the prognosis.