The essential oils from the USDA germplasm collection of anise hyssop (Agastache foeniculwn), catnip giant hyssop (A. nepetoides) and Korean mint (A. rugosa) and putative hybrids were field-grown and harvested during full bloom. The leaves were dried and the essential oils extracted via hydrodistillation to identify the major chemical constituents. Methyl chavicol was found to be the major compound in most accessions, and accounted for >92% of the total essential oil in six lines and one putative hybrid. Results indicated a wide range in the relative concentrations of other compounds ( cx-limonene, menthone, methyl eu,geno!, bornyl acetate, spathulenol, cadinol and !3-caryophyllene) and in essential oil content.