Introduction. Plant materials are susceptible to microbial contamination at all stages of the technological process and storage. This problem becomes highly relevant when extracting biologically active compounds from the Inonotus obliquus chaga mushroom. If used in food systems, contaminated extracts may cause their subsequent microbial contamination, as well as deterioration of quality and safety, which inevitably leads to economic losses and health risks. Inonotus obliquus is a popular component of various functional foods; therefore, the microbiological purity of its extracts requires a thorough analysis. In this regard, toxicity in a living test object is another important aspect of the safety studies of extracts and biologically active compounds. Before introducing a new food additive or component into the food system, it has to be tested for toxic properties. Study objects and methods. The research featured aqueous and supercritical CO -extracts of the Inonotus obliguus chaga mushroom. The aqueous extract was obtained according to the method specified in the State Pharmacopoeia of the USSR. The supercritical CO extraction was obtained using a Thar SFE-500F-2-FMC50 supercritical fluid extraction system. Microbiological indicators were determined by standard operating methods. The relative biological value and possible toxic properties were measured by biotesting on Tetrahymena pyriformis. Results and its discussion. During the entire tested storage period, the microbial contamination of the extracts remained at a low level, while the contaminants in the supercritical extract showed signs of microbial deactivation by carbon dioxide. The experiment on the ciliates demonstrated no inhibition of motility and growth, the shape of the cells was oval, even, and the cell walls remained unaffected, which means that the extracts produced no toxic effect. Conclusion. The extracts of the Inonotus obliguus mushroom proved to be biologically valuable and toxicologically safe. The test on Tetrahymena pyriformis showed stable and traceable microbiological indicators. Therefore, aqueous and supercritical CO extracts of Inonotus obliguus can be used in food industry. 2 2 2