Formulations containing potassium salts (eg, chloride, nitrate, citrate, oxalate) are widely used for treating dentin hypersensitivity (DH). The purpose of this review was to evaluate evidence for the clinical efficacy of potassium salts in reducing DH and also to consider the biologic basis for any effects. Literature searches were used to identify reports of clinical trials of potassium-containing preparations. Searches revealed 3 trials of potassium nitrate solutions or gels; 2 trials of mouthwashes containing potassium nitrate or citrate; 6 trials of potassium oxalates; and 16 double-blind randomized trials of toothpastes containing potassium nitrate, chloride, or citrate. The toothpaste studies provided quantitative data on treatment effects. These outcome measures were expressed as percentage reductions in sensitivity to cold air and mechanical stimulation and the patients' subjective reports. Trials of topically applied solutions yielded inconsistent results. Potassium-containing mouthwashes produced significant reductions in sensitivity. All potassium-containing toothpastes produced a significant reduction in sensitivity to tactile and air stimuli, as well as subjectively reported sensitivity. In most studies, the active agent (potassium) was superior to the minus-active control (placebo), but a few of the more recent trials have demonstrated significant placebo effects. It is postulated that potassium ions released from toothpastes diffuse along the dentinal tubules to inactivate intradental nerves. However, this principle has never been confirmed in intact human teeth. The mechanism of the desensitizing effects of potassium-containing toothpastes remains uncertain at present.