Tetracycline antibiotics are the products of the secondary metabolic streptomyces strains which show antibiogenic activity on different types of microorganisms. Due to their broad-spectrum activity, a relatively low toxicity and possible use in various pharmaceutical forms their application in human and veterinary medicine is significant. In this work we have conducted oxytetracycline biosynthesis through the submerged cultivation of Streptomyces rimosus in optimized conditions and tested the antibiotic activity of the filtrates of the S. rimosus culture and oxytetracycline according to selected test-microorganisms. We have determined the physiological indicators and the parameters of the biosynthesis of OTC with the S. rimosus bacterium during the 96 hours of cultivation: sterility test, microscopic image, the pH value of fermentated supstrate, the determination of the weight of the dry mycelia, the determination of the quantity of unused starch, the determination of the ammonia nitrogen, the colorimetric determination of the oxytetracycline. During the 96 hours, the concentration of the OTC increased and the final concentration was 1942 mg/ml. S. rimosus and OTC filtrates of different concentrations have shown a strong inhibitive action on the selected test-microorganisms. The substrate of Streptoyces rimosus has to contain all the necessary ingredients which will ensure a quality growth of the microorganisms and the oxytetracycline biosynthesis with optimal productivity. Moreover, it is necessary to monitor the conditions during the cultivation.