The microflora of the digestive tract is a complex microbial ecosystem, well balanced, which in an aboral direction undergoes specific changes as to the ratio of aerobic and anaerobic microorga- nisms the functions of which supplement each other - the aerobes ensure for the whole ecosystem the scavenger effect. The microbial profile of the digestive tract is typical by the absence of anaerobic microorganisms in the stomach and conversely their absolute predominance in the distal colon. The basic physiological functions of the microflora of the digestive tract can be characterized as follows: 1. microbial barrier against pathogens and potential pathogens, 2. for- mation of products of the microflora and their influence on the blood supply of the intestinal mucosa and peristaltics, 3. stimulation of the immune system in the gut, 4. reduction of bacterial translocation, 5. production of vitamins. To this problem in the world literature, contrary to ours, deserved attention has been paid for many years. Knowledge of the problem opens the door to expedient manipulation with the microbial flora of the digestive tract by the use of diet or prebiotics, probiotics as well as antibiotic treatment. The author presents a summary of basic findings which developed on the subject of physiological microflora of the digestive tract succes- sively up to their present shape.

        Key words: Digestive tract - Microflora of the digestive tract - Barrier against pathogens - Reduction of bacterial tranlocation