Abstract The essential oils of the two subspecies glandulosa and nepeta of Calamintha nepeta (L.) Savi are known to contain a p-menthane skeleton oxygenated in the C-3 position. The particular richness in piperitone oxide of the essential oil obtained from a sample of the ssp. nepeta collected in Urbino (Italy) allowed a chemotaxonomic distinction to be made between these subspecies. Key Word Index: Calamintha nepeta ssp. nepeta Lamiaceaeessential oil compositionpiperitone oxide