To examine the prognostic value of CSF abnormalities in seropositive autoimmune encephalitis (AE).We retrospectively studied 57 cases of seropositive AE. Primary outcomes were mortality and modified Rankin Scale, while secondary outcomes were first line treatment failure, ICU admission and relapse. Regression analysis was performed.CSF white cell count (WCC) was higher in the NMDAR group, while elevated protein was more common amongst other subtypes. We found an association between WCC >5 cells/mm3 and treatment failure (OR 16.0, p = 0.006)), and between WCC >20 cells/mm3 and ICU admission (OR 19.3, p = 0.026).Different subsets of AE have characteristic CSF abnormalities, which may aid recognition during early evaluation. CSF WCC had prognostic significance in our study.