The redundant bacterial growth syndrome in the small intestine is associated with the increased total semination of over 10(5) CFU/ml presented by enterobacteria, bacteroids, clostridia, fusobacteria, etc. It is developed at the dysfunction of the gastrointestinal tract, insufficient bacteria inhibition at the time when they come from the large intestine (atony, stasis, bypasses) and is accompanied by the enhanced intestinal barrier permeability along with chronic diarrhea and intoxication. Intestinal absorption disorders cause B12-deficiency anemia, hypovitaminosis and protein deficiency. The redundant growth is diagnosed based on the hydrogen concentration in the expired air or bacterial inoculation of the small intestine aspirate. Tetracycline, Vancomycin, Metronidazole and aminoglycoside are used for the therapy; Amoxicillin/clavunate and cephalosporins of the second generation are also applied with success. Decontamination of the small intestine is more successful when probiotics are prescribed (both after antibiotics and independently), which suppress the opportunistic flora, protect the mucous coat, improve digestion and arrest diarrhea. Probifor or Bifidumbacterin forte in the complex with probiotics comprising lactobacteria can also have a therapeutic effect.