目的了解恶性肿瘤患者血一氧化氮（ＮＯ）及丙二醛（ＭＤＡ）的变化及临床意义。方法以Ｇｒｅｅｎ硫代巴比妥酸法测定了６４例不同病期恶性肿瘤患者血ＮＯ及ＭＤＡ含量。结果恶性肿瘤患者血ＮＯ和ＭＤＡ较对照组高（Ｐ＜００１，Ｐ＜００５），各肿瘤组间ＮＯ及ＭＤＡ差异无显著性，而Ⅳ期肿瘤患者ＮＯ和ＭＤＡ低于Ⅱ、Ⅲ期患者（Ｐ＜００１）。结论ＮＯ和ＭＤＡ可能参与了肿瘤发生发展过程，而晚期肿瘤患者血ＮＯ和ＭＤＡ下降趋势有可能成为预后不良的临床指标。 Objective To understand the changes and clinical significance of nitric oxide (NO) and malondialdehyde (MDA) in patients with malignant tumors. Methods The levels of NO and MDA in blood of 64 patients with different stages of malignancy were measured by Green thiobarbituric acid method. Results The levels of NO and MDA in patients with malignant tumors were higher than those in controls (P<001, P<005). There was no significant difference in NO and MDA between tumor groups, but in patients with stage IV tumors, NO and MDA were lower than II. Stage III patients (P<001). Conclusions NO and MDA may participate in the process of tumor development. However, the decline of blood NO and MDA in advanced cancer patients may become a clinical indicator of poor prognosis.