Objective To investigate the diagnostic value of plasma ,peripheral blood mononuclear cell (PB-MC) and throat swab EB virus (SBV) load in the patients with infectious mononucleosis (IM ) aged over 16 years old .Methods The detection results in 130 patients with suspected IM aged over 16 years old of 3 differ-ent samples of plasma ,peripheral blood mononuclear cell(PBMC) and throat swab EB virus(SBV) load were analyzed retrospectively .Results Among 61 cases of IM verified by clinic and laboratory ,16 cases of IM were detected by plasma sample ,the detection rate of EBV-DNA was 26 .22％ ;in 31 cases of PBMC detection ,the EBV-DNA detection rate was 61 .29％ ;in 31 cases of throat swab detection ,the EBV-DNA detection rate was 83 .78％ .The EBV-DNA detection rate of the combined detection with one indicator or multiple indicators positive of plasma ,PBMC and throat swab as the basis was 100 .00％ .Conclusion The combined detection of plasma ,PBMC and throat swab can improve the positive rate in the patients with IM aged over 16 years old , w hich can provide more bases for pathogenic diagnosis and treatment for clinic .