Clinical course of Herpes Simplex Encephalitis were shown in this paper. 24 children in the age of 4 to 15 were treated at Polish Mother's Memorial Hospital in years 1992-1994. Value of EEG, CT scan, NMR were underlined in early diagnostic and casual treatment of diseases. All children from this analysis group survived, only 8 demonstrated late complications: epileptic attacks (3), spastic tetraparesis (1), encephalopathy and mental disturbances (1). Positive results of treatment were connected with early diagnosis and early antiviral treatment which is very important in decreasing death rate and preventing permanent injury.