The study objective was the assessment of the effect of anthills on changes in the physico-chemical properties in sandy soil. The research covered two sites (an anthill and a control object) in the Idzbark village in the Stare Jabłonki Forest District, N Poland. Soil samples were collected from the edges of an anthill (from the northern, southern, eastern, and western side), and at a distance of 13.5 m from it (control) from a depth of 0–25 cm. The samples were subject to the determination of soil pH in water and 1 mol KCl dm^-3 by means of the potentiometric method, content of available forms of potassium and phosphorus by means of the Egner-Riehm method, exchangeable cations in ammonium acetate, as well as content of total organic carbon, nitrogen, and sulphur on a CNS device. The soils proved strongly acidic at both sites, although in the case of the control sample the soil showed considerably lower pH in comparison to soil from the edges of the anthill. Ants also have an effect on the availability of important nutrients in the soil. The study revealed very high content of phosphorus and very low content of potassium in the sampled soil. The comparison of soil samples from the edge of the anthill with control showed that the activity of ants caused an increase in the content of available forms of potassium and phosphorus. In anthills, the content of exchangeable cations such as Ca²⁺, Mg²⁺, K⁺, and Na⁺ was usually higher than in the surrounding habitat. It is the most evident in the case of Mg²⁺ and K⁺ content in the anthill and in control. The activity of ants within the anthill positively affected the physico-chemical properties in sandy soil.