Abstract <p>The effect of grazing intensity on the physicochemical properties and biological activity of soils in mountain pastures of the Eastern Caucasus has been studied. The objects of the study are represented by Leptic Umbrisols developed on colluvium of the Upper Cretaceous limestones at 1620–1660 m a.s.l. Microbial biomass, enzymatic activity, and the sizes of the fractions in the pool of active soil organic matter have been determined. It is shown that intense grazing on the slopes of southern exposure causes a decrease in the content of C_org and microbial biomass, while pH values, carbonate content, urease activity, and the content of soil skeletal skeleton fractions increase. Intense grazing on the northern slopes results mostly in a decrease in the activity of β-glucosidase and an increase in the activity of alkaline phosphatase, as well as in the biomass of fungal mycelium. Intense grazing leads to changes in the structure of the active pool of soil organic matter. The time of complete decomposition of difficultly mineralizable carbon fractions in the zone of intense grazing on the slope of the northern exposure decreases twofold. A decrease in the content of potentially mineralizable and difficultly mineralizable organic matter is noted on the slopes of the southern exposure. At the same time, the content of easily mineralizable organic carbon decreases to a lesser extent. On the contrary, in the soils on the north-facing slope, intense grazing leads to a slight increase in the active pool of organic matter. Thus, the organic matter and biological activity of soils of the slopes of southern exposure in the mountainous zone of the Eastern Caucasus are more susceptible to the destructive influence of grazing, which should be taken into account when calculating the norms of pasture load.</p>