Astroglia are the homoeostatic cells of the central nervous system that control a normal function of synaptically connected neuronal networks and contribute to brain defense. Recent advances in comprehension of pathological potential of astroglia indicate that astrocytes are fundamental for most (if not all) neurological diseases. Neuropathological and neuroimaging studies demonstrate prominent astroglial atrophy and astroglial asthenia occurring in most of neuropsychiatric illnesses. In chronic diseases such as schizophrenia and major depression, decrease in astroglial numbers and functional capabilities are, arguably, fundamental for pathological developments being responsible for neurotransmitter disbalance and failures in connectivity within neural networks. In neurodegenerative diseases atrophic changes in astrocytes are complemented by astrogliosis triggered by specific lesions such as senile plaques or dying neurons, these two processes contributing to cognitive decline and ultimately neuronal death. It is therefore possible to hypothesize that neuropsychiatric diseases represent a chronic astrogliopathology, which compromises glial homeostatic and defensive capabilities, and the degree and the alacrity of gliodegenerative changes define the progression and outcome of these disorders.