Equilibrium headspace analysis in combination with gas chromatographylmass spectroscopy was used to identify volatile compounds released by the inflorescences and leaves from individual plants of Agastache foeniculum, Agastache rugosa, and putative hybrids. Methylchavicol was the major constituent in most populations tested. The inflorescences produced from 2 to 6 times more volatiles per gram than did the leaves. A. rugosa produced more volatiles than did A. foeniculum and had less diversity in its volatile composition. The putative hybrid was intermediate between the two proposed parents. The headspace analysis technique gave values comparable to those of traditional volatile oil extraction methods.