Abstract: This paper compared determined results of serum fibronectin of fifty-two patients with various malignant tumor in pre-and after-radiotherapy course with 50 healthful persons. The result showed shat the mean serum value of fibronectin for the patients with tumor in pre-radiotherapy(118.8±39.7μg/ml) Significant lower than normal person(186.9±39.4)(P0.001). The mean value of after-radiotherapy(154.9±53.1)had a rise significantly as compared with preradiotherapy(P0.001). Of overall 52 cases, all mean value of varrous patient's groups with nasopharynx cancer, other cancer of heat and neck, esophagus cancer, brain tumor or breast cancer had rised to compatible level with normal persons(P0.2～0.5). It was conclude that the determin of serum fibronectin may be a simple and convenient method as judging radiotherapy effect and prognosis.