Abstract: Objective To provide the evidence for excluding venous thromboembolism in patients with cancer during chemotherapy by investigating the change in their plasma D-Dimer concentration. Methods One hundred and one patients were divided into gastric cancer group,intestinal cancer group,and lung cancer group.Their plasma D-Dimer concentrations were measured by automatic immuno-turbidimetric assay and analyzed by ANOVA test in a general linear model. Results A significant difference was found in plasma D-Dimer concentration of patients with gastric,intestinal and lung cancer（F=8.634,P＜0.05）.However,no significant difference was found in plasma D-Dimer concentration of patients with gastric and intestinal cancer or with a single cancer（F=1.358,F=0.565,P＞0.05）.Cancer type and chemotherapy time had no combined action on plasma D-Dimer concentration（P＞0.05）. Conclusion Chemotherapy does not influence the plasma D-Dimer concentration in cancer patients.The difference in plasma D-Dimer level among different types of cancer suggests that the critical plasma D-Dimer cutoff value should be established for the prognosis of such cancer patients.