目的 分析小儿急性淋巴细胞白血病(急淋)缓解时和缓解不同时期微小残留病(MRD)的水平与复发的相关性。方法：用极限稀释定量PCR法和巢式PCR法追踪检测MRD，数据处理用KaplanMeier方法及COX回归模型等。结果：46例急淋患儿缓解时MRD值与骨髓复发呈正相关(r=0.4396，P<0.01)，骨髓复发组MRD值为7.359×10-3，与未复发组MRD值(3.954×10-4)差异有显著性(P<0.01)；缓解期MRD持续阳性或由阴性转为阳性者，骨髓复发的相对危险度明显增高(P<0.05)。结论：缓解时MRD水平及缓解期MRD定性结果可作为估计急淋预后的一个重要指标，动态追踪检测MRD是指导治疗和预防复发的有效手段。

OBJECTIVE: To study the relationship between bone marrow relapse and the level or changes of minimal residual disease (MRD) in childhood acute lymphoblastic leukemia (ALL). METHODS: The MRD level was detected using the modified limiting dilation PCR and nested PCR in 46 children with ALL; the data was analyzed using the Kaplan Meier method and COX model. RESULTS: The MRD level of the 46 patients by the time of complete remission (CR) was positively correlated with marrow relapse (r= 0.4396 ,P< 0.05 ). There was a significant difference in the MRD level between marrow relapse children and non relapse children ( 7.359 ×10 -3 vs 3.954 ×10 -4 ; P< 0.05 ). The cases whose MRD was persistently positive or changed from negative to positive during CR had a higher relative risk for relapse (P< 0.05 ). CONCLUSIONS: The MRD level by the time of CR and the qualitative findings in the period of CR are important markers in accessing the prognosis in childhood ALL. MRD detection by PCR can be used to identify the relative risk for relapse and make more effective treatment and prophylaxis regimens for relapse in childhood ALL.