Objective ToinvestigatethediagnosticvalueofADC withhigherbvaluefortheaggressivenessofprostatecancer. Methods 52patientswithpathologicallyprovedprostatecarcinomawerestudiedretrospectively.AllpatientsunderwentroutineMRI andDWIwithbvalueof1000and2000s/mm2.Accordingtothelocationoflesionfrombiopsyreport,aROIwasdrawnonADC mapatcancerousfociwithlowT2WIandhighDWIsignalintensityrespectivelyandtheADCvalueswerecalculated.Fociwereclassifiedinto highriskgroup(Gleasonscore≥8)andlow-intermediateriskgroup(Gleasonscore≤7).TheADCvaluesatb=1000or2000s/mm2between thetwogroupswerecomparedbyttest.ROCcurvewasusedtodeterminetheabilityofdifferentb-values.Relationshipsbetween meanADCvaluesinfociatb=1000or2000s/mm2andtumorGleasonscorewereassessedusingthe S pear m an test.Results Thereweresignificantdifferencesbetweenthehigh-riskgroupandthelow-intermediategroup(P<0.05)undertwob-values(b=1000s/mm2 andb=2000s/mm2).TheareaundertheROCcurveofb=1000s/mm2andb=2000s/mm2 ADCvaluesindifferentiatingthetwo groupswas0.858(P<0.05)and0.902(P<0.05)respectively,andnosignificantdifferencewasobservedintheAUCofbothgroups(P=0.222). ADCvaluesoftumorregionswerenegativecorrelatedwithtumorGleasonscoreat1000s/mm2(r=-0.709,P<0.05)and2000s/mm2 (r=-0.814,P<0.05)respectively.Although,nosignificantdifferencewasobservedinthecorrelationcoefficient(ρ)betweentwo groups(P=02.09).Conclusion ADCvaluesofbothb=1000and2000s/mm2havecorrelationwithGleasonscores.Thediagnosticperformanceof highb-value(2000s/mm2)ADCissuperiortonormalb-value(b=1000s/mm2)ADCinassessmentoftumoraggressiveness.