Abstract: Objective To investigate the advantages ofpediatric critical illness score(PCIS) and the pediatric risk of mortalityⅢ(PRISM Ⅲ) in the judgment of the severe extent and prognosis in children with hand-foot-mouth disease and encephalitis. Methods PCIS and PRISM Ⅲ were sued to assess the severity of children with hand-foot-mouth disease and encephalitis.The patients were divided into three groups(very critical,critical,noncritical group) according to the scores.The mortality was calculated and compared among the three groups.The specificity and sensitivity of PCIS and PRISM Ⅲ in the judgment of the death risk in children hand-foot-mouth disease combined with encephalitis were compared through measuring the area under the ROC curve(AUC). Results ①PCIS score:To compare the mortality of the groups of non-critical,critical and very critical subgroups,the difference was statistically significant(8/466,10/12,5/5,χ²=93.099,P＜0.001).②PRISM Ⅲ score: To compare the mortality of the corresponding groups,the difference was statistically significant(4/458,4/7,15/18,χ²=114.579,P＜0.001).③The comparison between PCIS and PRISMⅢ score: the differences were not statistically significant in mortality between the two groups of non-critical,critical and critical subgroups,respectively(1.72% vs. 0.87%,χ²=1.282,P=0.258,88.24% vs. 76.00%,χ²=0.349,P=0.555).④Multiple logistic regression analysis revealed heart rate,blood pressure(systolic blood pressure) and renalfunction of PCIS sore and the state of consciousness and bloodglucose of PRISM Ⅲ score had more effective prediction of the death risk(P＜0.05,respectively).⑤The area under the ROC curve(AUC) for PCIS and PRISMⅢ were 0.929 and 0.985,respectively. Conclusion PCIS and PRISM Ⅲ score,with high specificity and sensitivity,can be used in the judgment of the severe extent and prognosis of children with hand-foot-mouth disease and encephalitis.