Objective: To evaluate the antimicrobial potential of five herbal toothpastes using the log reduction assay. Methods: Five randomly selected herbal toothpastes for the evaluation of antimicrobial potential were: 1) Dental Gel; 2) Herbal Brite; 3) Nutrismile C; 4) Vicco; and 5) Tom’s of Maine Natural Toothpaste. Colgate Total Plus Whitening toothpaste served as the positive control. Fresh cultures of three oral microbes, S. mutans (ATCC 25175), A. viscosus (ATCC 19246) and C. albicans (ATCC 18804), were prepared for each experiment. To determine the bactericidal potential, the mixture of toothpaste supernatant and microbial culture was incubated at 37oC for 10 minutes; sample aliquots were diluted in the media; and the mixture was then plated. Samples for the bacteriostatic assay were processed using the same procedures except the incubation time. Aliquots of 0.1 mL mixture were added to 10.0 mL medium and the mixture was incubated at 37oC for 48 hours. Counts of surviving cells were determined using the plate-count method, and the log reductions of microbes were calculated for each group. Results: In the bactericidal assay, three (Dental Gel, Tom’s of Maine Natural Toothpaste and Vicco) of the five herbal toothpastes produced ³3 log reductions in all three microbes; while only one (Dental Gel) induced ³3 log reductions in all three microbes in the bacteriostatic assay. The log reductions of Colgate Total Plus Whitening (positive control) in the three microbes were >5.71 and >5.77 for bactericidal and bacteriostatic assays, respectively. Conclusion: One of the five herbal toothpastes evaluated has significant antimicrobial efficiency that meets the FDA requirement for ³3 log reductions (1994); however the antimicrobial potential of herbal toothpastes may vary significantly and some have little antimicrobial effect.