In two children affected with "Epilepsia Partialis Continua" (EPC) of progressive type, probably secondary to a slow encephalitis, the percentage of T-lymphocytes in CSF was lower than normal (30% compared to 90%). The CSF-T-lymphocytes are characterized by their ability to form E-rosettes. In one patient signs of intrathecal synthesis of IgG, especially oligoclonal bands at isoelectrofocusing, were observed. These results confirm, that in this type of EPC some immunological parameters in the CSF are impaired; so the aetiological hypothesis of an infectious disease, caused by a non-conventional viral agent, is supported.