In the experiment accomplished, the effect was investigated of two types of fructans: short-chain fructooligosaccharides (FOS) and long-chain inulin, on the blind gut physiology in rats. Three diets were applied in the experiment: control diet (K) contained 7.5% of saccharose, and two other experimental diets contained: 8.3% of inulin (IN) and 7.9% of the FOS preparation (FOS) (commercial preparations). Young male rats of the Wistar breed (8 rats per one group) were fed ad libitum during 4 weeks. The individual feed consumption rates and gains in body weight of rats were determined. The following parameters was measured, among other things: the weight of tissue and of blind gut fill, pH, dry matter, ammonia, protein, volatile fatty acids (VFA), and activity of bacterial enzymes in the blind gut fill. No statistically significant differences in the total dietary food intake rate and in gains in body weight of rats among the experimental groups were found. The consumption of diets containing FOS and inulin caused a considerable increase in the weight of blind gut wall and fill (P < 0.05) compared to the control group. In the experimental groups, an increase was found in the concentration rates of protein and dry matter in the blind gut fill. The significantly lower (P < 0.05) values of pH and ammonia contents were found in the animals fed with the dietary food containing FOS and inulin. When fructans were added to the dietary food, the level of VFA increased per 100g of the body weight (LFA pool). The inulin impacted the production of VFA more beneficially than FOS, especially, it generated a statistically significantly increase in the content levels of propionate and butyrate acids in the blind gut fill. Furthermore, the inulin impacted the enzymatic activity of blind gut micro-flora more effectively than FOS. In the IN group, the lowest level of the activity of β-glucuronidase was found, whereas the β-glucuronidase is a biomarker of the activity of pathogenic micro-flora.