The effects of inhalation of L-menthol, D-isomenthol and D-neomenthol, upon nasal resistance and sensation to airflow were investigated in 40 subjects. L-menthol caused a highly significant enhancement of nasal sensation of airflow but despite their great similarity in structure and a similar peppermint smell the isomers D-isomenthol and D-neomenthol had no effect on nasal sensation of airflow. These findings show that L-menthol has a specific pharmacological action on nasal sensory nerve endings which is not related to its peppermint smell.