目的　探讨过敏性紫癜 (HSP)、紫癜性肾炎 (HSPN)患儿血清一氧化氮 (NO)的改变。方法　观察HSP患儿 2 4例、HSPN患儿 15例、健康儿童 30例。采用硝酸还原酶法测定血清NO含量。结果　HSP ,HSPN患儿血清NO均明显增高 ,与对照组比较差异有高度显著性 ;HSPN与HSP患儿血清NO相比差异无显著意义。结论　NO参与了HSP ,HSPN的发病过程 ,为临床应用NO拮抗剂治疗该病提供了依据。 Objective To investigate the changes of serum nitric oxide (NO) in children with Henoch-Schonlein purpura (HSP) and purpuric nephritis (HSPN). Methods 24 cases of HSP, 15 cases of HSPN and 30 healthy children were observed. Nitric acid reductase method for determination of serum NO content. Results The levels of serum NO in HSP and HSPN children were significantly higher than those in control group, but there was no significant difference in serum NO between HSPN and HSP children. Conclusions NO participates in the pathogenesis of HSP and HSPN and provides the basis for the clinical application of NO antagonist in the treatment of this disease.