Probiotics are bacteria that are commercially available as dietary supplements. One of the important properties of probiotics is their ability to survive in the intestine. Recent evidence has identified kynurenic acid (KYNA) as a bactericidal constituent of intestinal fluid. These data led us to study the influence of KYNA on the viability of selected probiotics. We found that KYNA supported the growth of bacteria in the probiotics Acidolac (Lactobacillus acidophilus, Bifidobacterium) and Lakcid Forte (Lactobacillus rhamnosus) or retarded the growth of bacteria from the Acidolac, BioGaia (Lactobacillus reuteri Protectis), Dicoflor (Lactobacillus rhamnosus GG), Lacium (Lactobacillus plantarum) and Trilac (Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. bulgaricus, Bifidobacterium animalis subsp. lactis) probiotics depending on its concentration. KYNA did not affect the viability of bacteria from the probiotic Linex (Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12). Our results suggest a potential role of KYNA in the regulation of bacterial growth in the digestive system.