Results: The gross and microscopic structure did not reveal any specific changes. In the encephalopathy group, HHV-6 DNA sequence was found in meningeal tissues (16/21 cases; p=0.0036), in brain tissues (15/21 cases; p = 0.0007), and both in brain and meningeal tissues (10/21 cases; p=0.0174). In the control group, the viral DNA was identified in meningeal tissues (7/23 cases), in brain tissues (4/23 cases), both in brain and meningeal tissues (3/23 cases). HHV-6B variant was detected in all cases. Conclusion: On the basis of the present study it can be concluded that HHV-6 is a pathogenic factor that can predispose to encephalopathy.