Essential oils and headspace of 14 different clones ofAgastache foeniculumwere obtained by hydrodistillation and by purging the plant material with nitrogen gas, respectively. The constituents of both the oils and headspace were analyzed by capillary GC and GC/MS. Over 50 compounds were detected in oils isolated by the two extraction procedures. Only ten constituents, however, accounted for more than 0.1% and methyl chavicol constituted 95–98% of the essential oil. Yield and quality of oil were only marginally affected by year of production and time of harvest of the plant material.