Objective: The morphology of non-specified encephalopathy is a complex medical problem. Human herpesvirus-6 (HHV-6) infection can be discussed as a predisposing factor. The aim of the present study was to investigate the presence of beta HHV-6 in non-specified adult encephalopathy cases. Method: The blood, meninges and brain tissue were obtained in adult (aged 42-74 years) autopsies including 21 cases with encephalopathy and 23 cases in the control group. Tissues were submitted for routine histology including haematoxylin-eosin stain. The presence of HHV-6 genome (DNA) was analysed by nested polymerase chain reaction (nPCR), HHV-6 variants by restriction endonuclease analysis.