Objective To search for the main differential points in clinical features and CSF findings in patients with central nervous system infectious diseases caused by different pathogens.Methods 296 cases with infectious diseases in central nervous system were studied retrospectively.Clinical features and CSF findings before administration of specific antibiotics were compared.Results Viral meningitis or encephalitis (VM) and purulent meningitis (PM) patients usual had high fever(62% and 67%).60% cryptococcal meningitis (CCM)patients had headache without fever at the onset.The incidences of convulsion in VM were higher than those in the others (63%).The incidences of failing eyesight (40%),hearing defeat (45%),optic papilla edema (74%) and brain hernia (42%) in CCM patients are higher than the other groups.Paralysis is more common in VM patients (55%) than that in the others.The leukocytosis of peripheral blood in PM patients is remarkable (64% over 20 × 109/L),with polymorphonuclear leukocytes predominating.CSF examinations:the patients CCM have much higher initial CSF pressure (91% over 3.96 kPa).Elevation of leukocytes in PM patients is most significant (76%over 400 × 106/L).The concentration of sodium chloride in the PM (74%) and tuberculous meningitis (TBM 82%) patients often reduced.Extreme elevation of the protein (2 g/L or more) was usually observed in TBM patients (48%).Conclusion The patients with CCM and TBM were similar in manifestations and the findings of CSF.The CSF pressure and the level of protein in CSF were the important markers for their differential diagnosis.It is more easy to make a diagnosis in PM or VM patients.