Human herpesvirus 6 (HHV-6) is one of the recently discovered herpesviruses. Primary HHV-6 infection is a causative agent of roseola infantum and is frequently associated with nonspecific febrile seizures in children under the age of 3 years. The goal of our study was the investigation of HHV-6 infection in children with febrile seizures and to evaluate consequent seizures after the first episodes of febrile seizures associated vs. not associated with primary herpesvirus 6 infection during 12 months time period. 25 children with (study group) and 25 without (control group) HHV-6 infection have been investigated. Laboratory investigations included detection of anti-HHV-6 specific IgM and IgG antibodies by ELISA and of HHV-6 DNA by polymerase chain reaction ("home-made" PCR as well as Chemicon Light Diagnostics Oligo-Detect Assay). The clinical severity of the febrile seizures was not statistically different between the study and control groups. The recurrence rate was higher in the study group. Our study shows that s first febrile seizure associated with the primary HHV-6 infection corresponds to the reduced risk of development of recurrent seizures.