The inhibition of Streptococcus mutans by Coffea arabica extracts incorporated or not with natural coffee compounds was investigated by the disk diffusion method. Additionally, the turbidimetric test was used to verify the influence of caffeine concentration on the inhibition of S. mutans. Extracts of different samples of Arabica coffee showed antibacterial activity against S. mutans. The inhibitory effect was not affected by the brewing method (filtered or espresso) or by the different Arabica coffee samples. Plain caffeine, trigonelline, caffeic acid, protocatechuic acid and chlorogenic acid at 2.0 mg/mL provided similar antimicrobial effect against S. mutans. However, there was an increase in the antibacterial activity when these compounds were added to the coffee extract, except for chlorogenic acid which did not affect the inhibitory effect. Caffeine at concentrations found in Arabica beverages inhibited S. mutans temporarily, whereas higher caffeine concentrations provided a stronger and longer lasting inhibition.