The purpose of this experimental research "in vitro" was to compare the antibacterial effect of the ethanolic extract of Aloe vera (L) and Curcuma longa L., on the growth of Streptococcus mutans ATCC 25175. Ethanolic extracts of Aloe vera ( L) and Curcuma longa L. at concentrations of 25%, 50% and 75% each. The Streptococcus mutans strain ATCC 25175 was reactivated in brain heart broth. To evaluate the antibacterial effect, 10 repetitions of each concentration were carried out using the Kirby Bauer method, making use of filter paper disks placed in plates containing Müeller Hinton Agar-blood inoculated with S. mutans. Chlorhexidine 0.12% was used as a positive control and distilled water as a negative control. The diameters in (mm) of the inhibition halos around each disc were measured with a vernier pachymeter. The ethanolic extract of Curcuma longa L. did not present inhibition halos ...