Oral malodor, also known as bad breath or halitosis, is an extremely common problem. Bad breath can arise from many sources in the body, but most frequently is produced in the mouth by the action of gram-negative anaerobic bacteria on sulfur-containing proteinaceous substrates in the saliva, such as debris and plaque. The primary molecules responsible for oral malodor are volatile sulfur compounds (VSC), such as hydrogen sulfide and methylmercaptan. Increased malodor production is related to greater bacterial numbers, reducing conditions, availability of protein substrates, and a pH above neutral. Bad breath is more common in the elderly, as well as those with unhygienic mouths, gingivitis, and periodontitis, but bad breath can also be found in some individuals who are periodontally healthy. The major source of oral malodor is the tongue. Approaches to controlling malodor have included masking, oral hygiene, antibacterial agents, conversion of VSC to nonodorous forms, oxidizing agents, and traditional approaches, including the use of baking soda. Results of controlled double-blind crossover studies, using both organoleptic (sensory) and gas chromatographic analysis of mouth air VSC, indicate that two dentifrices with high baking-soda concentrations, Arm & Hammer Dental Care and Arm & Hammer PeroxiCare, reduce oral malodor.