Aims. As the most abundant cells in the central nervous system, astrocytes include two morphological forms (protoplasmic and fibrous), providing structural and functional support for the neurons. Their number and cytoarchitecture are frequently affected by neurodegenerative diseases and aging. The scope of this study was to evaluate the morphological changes of the principal olivary nucleus (PON) astrocytes during physiological aging using geometrical and fractal analysis. Methods. The study sample consisted of 30 two-sided sections of the principal olivary nucleus divided into three age groups (the second period of maturation (36-60 years), early aging (61-75 years), and late aging (76-90 years)). Microscopic images of histological sections were digitized and then transformed into binary and skeletonized forms. Images of 294 astrocytes (146 protoplasmic and 148 fibrous) were quantitatively evaluated, and the analysis of the size, shape, branching, length, and cell complexity was carried out by calculating 9 (geometric and fractal) parameters. Results. The body area, parameters of the astrocyte length, and the astrocyte arborization complexity were significantly lower in the sample of the third age group compared with the first and the second. Conclusions. The late aging period of the nervous system resulted in regressive changes in glial cells. During the early aging period, astrocytes undergo atrophic changes in the body, glial field, and processes, and morphological remodeling continues during further aging.