Recent years have brought a huge increase in awareness about probiotics and their beneficial effects on the human organism. The field of food technology continues to meet consumers and creates new solutions, such as plant-based alternatives to dairy products containing probiotic bacterial strains. The aim of the study was to determine whether the probiotic strains of Lactobacillus acidophilus La-5 and Lactiplantibacillus plantarum 299v would effectively ferment beverages based on lentils and oats. The test results indicate that the strains used show the fermentability of plant-based beverages, and the products obtained as a result of storage in refrigeration conditions retain the number of lactic bacteria appropriate for probiotic products.