The microflora of the intestinal tract is vital to many physiological functions, mainly fermentation and processing of dietary components, control of intestinal epithelial cell proliferation, development of the immune system, and protection against pathogens. Plant extracts have potential for treatment options that protect commensal or beneficial microflora in the intestines while eliminating pathogens. The aim of the present study was to investigate the influence of Pinus brutia (Turkish red pine) bark extract containing phenolic compounds on some commensal and pathogenic bacteria from the intestinal microflora using a microdilution method. P. brutia bark extract did not completely inhibit any intestinal bacteria. However, the extract showed a potential inhibitor activity on Salmonella Typhimurium and Staphylococcus aureus from 75 µg/mL, on Escherichia coli and Fusobacterium nucleatum from 150 µg/mL, and on Clostridium perfringens from 300 µg/mL concentrations (P<0.05). Commensal bacteria were observed to be less sensitive to the extract than those of the pathogenic strains. The extract stimulated moderately the growth of Bifidobacterium bifidum from 75 µg/mL dose (P<0.05). The extract did not show any activity on Lactobacillus acidophilus. A potential inhibitor activity was observed for Bifidobacterium infantis and Lactobacillus casei at 600-2400 µg/mL (P<0.05). As a conclusion, P. brutia bark extract, at 75-300 μg/mL dose range, had a potential to restrict pathogenic bacteria in the intestines while protect commensal or beneficial ones. Specified effects might be mainly attributed to its polyphenolic content.