Menthol and related cooling compounds such as 'coolant agent 10', are widely used in products ranging from common cold medications to toothpastes, confectionery, cosmetics and pesticides. The review brings together a range of information on production and chemistry of menthol, and its metabolism, mechanism of action, structure-activity relationships, pharmacology and toxicology. In particular, the coolant action and carminative actions of menthol are discussed in terms of actions on calcium conductance in sensory nerves and smooth muscle. The actions of menthol on the nose, respiratory reflexes, oral cavity, skin and gastrointestinal tract are reviewed.