The objective of this randomized, crossover study was to compare the effectiveness of a newly designed manual toothbrush (Colgate 360 degrees) to two commercially available manual toothbrushes (Oral-B Indicator and Oral-B CrossAction) and a battery-powered toothbrush (Crest SpinBrush PRO) for their ability to reduce hydrogen-sulfide-forming bacteria on the tongue. After a washout period, subjects arrived at the clinical site for baseline sampling without performing dental hygiene, eating, or drinking. Subjects sampled the left side of their tongue with a cotton swab. Subjects brushed for 1 minute with the assigned test toothbrush and regular fluoride toothpaste. Those using the Colgate 360 degrees toothbrush were instructed to clean their tongue with the implement on the back of the brush head for 10 seconds. After 2 hours, the subjects returned to the clinical site having refrained from dental hygiene, eating, and drinking for posttreatment sampling, this time sampling the right side of their tongue. After a minimum 2-day washout period, subjects repeated the same regimen using the other toothbrushes. Collected tongue samples were dispersed in sterile water, serially diluted in sterile phosphate-buffered saline, and plated in duplicate onto lead acetate agar. When plated on this medium, bacteria that produce hydrogen sulfide appear as dark-pigmented colonies. After 72 hours of incubation, the dark colonies were counted, expressed as log colony-forming units/mL, and reduction from baseline was calculated. Thirty-one adult men and women completed the clinical study. There was no significant difference between baseline hydrogen-sulfide-forming bacteria levels. Posttreatment, the log reduction of bacteria was 0.80, 0.41, 0.33, and 0.44 for the Colgate 360 degrees, Oral-B Indicator, Crest SpinBrush PRO, and Oral-B CrossAction, respectively. Statistical analysis indicated that the Colgate 360 toothbrush was statistically significantly better (P < .05) than the 3 commercial toothbrushes in reducing the levels of hydrogen-sulfide-forming bacteria on the tongue.