Currently, there is a growing demand in antioxidant preparations designed to neutralize the negative consequences of oxidative stress induced by a series of environmental factors, like UV rays, invasion of pathogens, herbicides action, pollution etc. Mannoproteins from yeast cell walls manifest antioxidant, immunomodulatory, anti-neoplastic and antibacterial activity, which makes them widely applicable in medicine, pharmacology, food industry, wine making, cosmetology etc. In the Republic of Moldova there are no mannoproteic preparations obtained from yeasts. Of a special scientific interest is the use of yeasts from Saccharomyces genus as an important source of biologically active substances with antioxidant effect. The aim of the present work was to determine the antioxidant activity of the mannoproteic preparation obtained from Saccharomyces cerevisiae CNMN-Y-18 yeast strain. The analyses were conducted at the Laboratory of Ficobiotechnology of the Institute of Microbiology and Biotechnology of the Academy of Sciences of Moldova. We determined the antioxidant capacity of the mannoproteic preparation using the cationic radical 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). The analysis of the obtained data proved an increased activity of reduction of ABTS radical by the mannoproteic bioproduct. Thus, together with the increase of the tested preparation concentration increases the value of the Trolox equivalent antioxidant capacity (TEAC) coefficient. The antioxidant activity of 10 mg of mannoproteic preparation is 52% inhibition ABTS that is similar to the concentration of 8 mg/mL. In order to determine the decisive role of the concentration of the manoproteic preparation we conducted correlational analysis of various concentrations of the mannoproteic preparation and the inhibition percent. The results showed a strong correlation between these two factors (R2 = 0,948). The method of ABTS radical release may be used to determine the antioxidant activity of the mannoproteic preparation obtained from Saccharomyces cerevisiae CNMN-Y-18 yeast strain, and the test value depends on the concentration of the preparation in range of 1-10 mg/mL.