Abstract Chemical composition of the essential oils obtained by hydrodistillation of the leaves (before and at full flowering stage) and flowers of Heracleum persicum L. were investigated by a combination of GC and GC/MS. Twenty-one components were characterized for the leaf oil before flowering with (E)-anethole (60.2%) and (E)-Î²-ocimene (8.4%) as the main constituents. At the full flowering stage, 19 compounds were identified in the leaf oil with (E)-anethole (47.5%), 2-propanone, l-(4-methoxy phenyl)-2-propanone (18.1%) and anisaldehyde (8.9%) as the major components. Among 21 compounds identified in the flower oil of H. persicum, the major constituents were (E)-anethole (38.6%), Î³-terpinene (17.8%) and myrcene (13.5%).