Chronic oral malodor is a serious concern for about one-fifth of the North American population, and a field of emerging research interest. The present three studies, one involving gas chromatography and two employing odor judge assessment, examined the efficacy of baking soda and other toothpastes in reducing breath odor. The most common cause of oral malodor is elevated levels of volatile sulfur compounds (VSC's), primarily hydrogen sulfide (H2S) and methyl mercaptan (CH3SH), in the breath. Gas chromatography, an accurate means of measuring breath VSC, was employed to evaluate the breath levels of VSC in 11 men after brushing with baking soda-containing dentifrices with or without the addition of Zn++. Dentifrices with either Zn++ or a concentration of baking soda 20% or greater significantly reduced VSC levels. The addition of Zn++ to baking soda dentifrices enhanced the anti-odor effects. In the first organoleptic study, dentifrices containing 20% baking soda and 30% baking soda demonstrated significantly greater ability to reduce breath odor than a standard sodium fluoride/silica dentifrice. The subjects' baseline mouth odor evaluations, initially rated as strong, declined after brushing with the baking soda toothpastes to a barely detectable level at one hour, then rising to a faint level at two hours and moderate levels at three hours. In the second organoleptic study, a dentifrice containing 65% baking soda demonstrated significantly greater ability to reduce breath odor than a standard sodium fluoride/silica tartar control dentifrice, but did not differ significantly from a standard dentifrice containing 0.76% sodium monofluorophosphate in a dicalcium phosphate dihydrate base. The results of these studies indicate that dentifrices containing 20% or more baking soda can confer a significant odor-reducing benefit for time periods up to three hours.