Astrocytosis is one of the hallmarks of neuropathology of transmissible spongiform encephalopathies (TSEs) or prion diseases. In this review, we summarize data on astrocytic reaction, including naturally occurring or experimentally induced TSEs. A particular form of astrocytic reaction is known as gliocytosis and it is typical for experimental scrapie in mouse or in hamsters. Also, astrocytes participate in the formation of amyloid plaques. An interesting interaction between astrocytes and oligodendrocytes is discussed in detail as well as a particular form of astrocytic reaction in panencephalopathic form of TSEs.