In this report, characteristics of two cases of Herpes simplex virus (HSV) encephalitis with normal cerebrospinal fluid (CSF) findings at the time of admission have been discussed and the current literature has been reviewed. The diagnosis of the cases (one was 23 years old male, and the other was 75 years old female patient) was made on the magnetic resonance imaging (MRI) findings concordant with HSV encephalitis, together with HSV-1 DNA positivity by polymerase chain reaction (PCR). Both of the patients were treated with acyclovir (3 x 750 mg/day) lasting for 15 days and 21 days, respectively. The first male patient recovered with mild neurological defects, whereas the second female patient died because of nosocomial pneumonia and septicemia. In conclusion, even the CSF findings are normal, in cases considered to be HSV encephalitis, MRI should be the first radiological diagnostic step and the diagnosis should be confirmed by the detection of HSV DNA in CSF by PCR.