Objective To evaluate the value of detecting abnormal lymphocyte morphology in peripheral blood and Epstein Barr Virus(EBV)DNA quantity through real-time quantitative PCR (RT-qPCR)in the initial diagnosis for infants patients with infectious mononucleosis (IM).Methods From Jan.2013 to Dec.2014 212 infants patients with IM were analysed ret-rospectively,which were all in-patients in the hospital.The abnormal lymphocyte morphology in peripheral blood and Epstein Barr Virus (EBV)DNA quantity were both detected in the initial fever period and a week later.The latter was detected by real-time quantitative PCR (RT-qPCR),combined with all the symptoms were all analysed comprehensively.The percentage of abnormal lymphocyte more than 10% was positive,and the EBV-DNA quantity more than 1.0×103 copy per ml was posi-tive,too.Results Of all the infants patients,in the initial fever period,82 patients had more than 10% positive abnormal lymphocyte and 100 patients had positive EBV-DNA quantity.But a week later,156 patients had more than 10% positive ab-normal lymphocyte,the maximum abnormal lymphocyte was 56%.And 180 patients had positive EBV-DNA quantity.When both abnormal lymphocyte morphology in peripheral blood and Epstein Barr Virus (EBV)DNA quantity were detected,in the initial fever period,125 patients were positive,it rose significantly more than that of abnormal lymphocyte morphology in peripheral blood (χ2=17.45,P<0.01),and that of Epstein Barr Virus (EBV)DNA quantity,too (χ2=5.92,P<0.05). But a week later,190 patients were positive,it rose significantly more than that of abnormal lymphocyte morphology in pe-ripheral blood (χ2=18.16,P<0.01).There was no significantly rising more than that of Epstein Barr Virus (EBV)DNA quantity (χ2=2.12,P>0.05).Conclusion The detecting of peripheral blood cell morphology combined with EBV-DNA
quantity are very important in the initial diagnosis for infants patients with infectious mononucleosis.Including all the symp-toms,they could improve the diagnosis timely and accurately.