Human herpesvirus 6 (HHV-6) is a beta-herpesvirus widely spread within a population and has been recognized as a potential significant pathogen in immunocompromised patients. Different clinical manifestations have been described including fever, skin rash, pneumonia, graft rejection and encephalitis. The goal of the study was development of real-time PCR assay for detection of human herpesvirus type 6 DNA in clinical samples, using primers targeting a conserved region of the viral DNA polymerase gene and a specific TaqMan hydrolyzing probe. The analytical sensitivity of assay was tested using serial dilutions of HHV-6 DNA in range between 10(0) and 10(-6). Thirty plasma samples taken from a group of adult recipients of allogeneic HSCT were tested for the presence of HHV-6 DNA in the LightCycler system. For comparison commercial quantitative MutaREAL HHV-6 kit (ALPCO) was used, according to the manufacturer's instructions. Both LightCycler assays, including in-house real-time PCR, detected HHV-6 DNA in 13 specimens. The conclusion is that developed TaqMan-based probes real-time PCR test is very reliable and valuable for detection of low-copy viremia in plasma samples. The high level of sensitivity and accuracy provided by the LightCycler instrument is favorable for the use of this method in the detection of HHV-6 DNA in clinical specimens.