Abstract: Objective To analyze the virus IgM situation in serum and cerebrospinal fluid of neurology patients with suspected acute central nervous system (CNS) symptoms in Tiantan Hospital from August 2013 to February 2015, and to elucidate the current etiologic spectrum. Methods 788 cerebrospinal fluid (CSF) and corresponding serum samples from outpatients and inpatients suspected of being intracranial infection were detected to find virus-specific and toxoplasma gondii-specific IgM antibodies by using enzyme-linked immunosorbent assay (ELISA) and electrochemiluminescence immunoassay (ECLIA). The positive results of these specific IgM antibodies were compared between serum and CSF samples using the chi-square test. Results Epstein-Barr virus (EBV) got the highest IgM detection rate in serum, followed by herpes simplex virus (HSV) and rubella virus (RUB) antibodies with detection rate 6.0%, 5.2% and 2.2% respectively. For the rest virus and toxoplasma gondii, the antibodies detection rates were about 1% in serum. In cerebrospinal fluid, however, the majority of the IgM was HSV antibody, its detection rate was 4.7%, about  92.5% of all detectable antibodies. The detection rate of virus-specific IgM antibodies was higher in serum than in the cerebrospinal fluid. The detection rate of HSV antibodies in serum samples was higher than their corresponding CSF samples, with a statistically significant difference between these two groups (P<0.01, chi-square test). Similarly, compared to CSF group, the IgM antibodies of EB virus and coxsackie virus (Cox V) also showed a higher detection rate in serum with the statistically significant difference (P<0.01 and P=0.039). For seasonal distribution, the CNS virus infection mainly occurred in spring, autumn and winter. The infection rate for different age groups had no significant difference. Conclusion Herpes simplex virus may be the main pathogens in patients suspected of being intracranial infection. In serum, EBV has the highest IgM detection rate in serum, followed by HSV. However, HSV-IgM has the highest detection rate in CSF. These above two kinds of virus are the main pathogens of the central nervous system infection, and must be paid more attention in clinical practice.