Objective To study the effect of different strains of mice(KM and ICR)immunized with rabies vaccine on thedetection of titer.Methods The rabies vaccine and the national standard for the efficacy verification of rabies vaccine forhuman use(referred to as national standard)were diluted with PBS at the ratios of 1∶25,1∶125,1∶625 and 1∶3 125,and KM and ICR mice with half male and half female were immunized intraperitoneally respectively.Sixteen mice of each strain wereimmunized with 0.5 m L/mouse at each dilution.The immunization was strengthened once every one week at the same dose androute.The mice in each group were weighed 0,7 and 14 d after the initial immunization.After 14 d of the initial immunization,the mice were subjected to intracranial attack with rabies virus(RABV)CVS2(5-100 LD_(50)),0.03 m L/mouse.The numberof mice with death and typical rabies brain symptoms 5 d after the attack was counted.According to the national standard ED_(50),the relative efficacy was calculated by Reed-Muench method.Results The body mass of the two strains of miceshowed an increasing trend during the immunization stage,and the body mass of KM mice increased faster than that of ICRmice.The lgED_(50) values of the national standard in KM mice were all within the expected range of 2.10-2.75,while thevalues in ICR mice were higher than the range.The titers of rabies vaccine in KM mice were all significantly lower than thosein ICR mice(t = 2.887-6.619,each P < 0.05).Conclusion Mouse strains can significantly affect the results of rabies vaccine titer determination,and different standards should be adopted for different strains of mice to ensure the accuracy of vaccine detection results.