The goal of the research was to evaluate the effects of inulin (Raftiline®) and fructooligosaccharides (Raftilose®) on the production of lactic acid and its isomers by Lactobacillus strains. Control cultures were grown in the presence of monosaccharides (glucose, galactose, fructose) and disaccharides (lactose, sucrose). The levels of L(+) and D(-) lactic acids were evaluated using the enzymatic tests of Boehringer Mannheim. It was found that the amount of lactic acid produced by Lactobacillus strains in MRS medium with fructosaccharides was 2.62 g/l on the average, which was much less than in the case of using media with mono – or disaccharides (9.31 g/l). The average amount of L(+) lactic acid varied from 0.70 g/l (in the medium with Raftiline®HP) to 7.69 g/l (in the medium with glucose). The ratio of isomer L(+) to isomer D(-) in the medium with fructooligosaccharides was 3.11 on the average, while in the medium with monosugars it was 3.14.