The present study was made to investigate the effect of xylitol on the bactericidal and bacteriostatic action of chlorohexidine diacetate (CHX) and sodium fluoride (F) in ATCC strains of Streptococcus mutans and S. sanguis. Standardized bacterial cell suspensions were used in tests for bactericidal effect and for inhibition of growth and sucrose fermentation. The results showed no interference of xylitol with the antibacterial effect of CHX and F combinations. Xylitol did not show any additive effect either but appeared inert in the combinations used.