The essential oils of flower and leaves of Phlomis grandiflora H.S. Thompson var. grandiflora (Lamiaceae), endemic grown in Turkey, were obtained by hydrodistillation and analyzed by gas chromatography (GC) and GC-mass spectrometry. The yields of essential oil isolated by steam distillation from the flowers and leaves of Phlomis were 0.12 and 0.2% (w/w), respectively. Hydrodistillation of the dried flowers and leaves of Phlomis gave light-yellowish oils. Thirty-two components were identified in the flowers oil, which represented about 92.1% of the total composition of the oil. The major constituents of the flower essential oil were β-eudesmol (61.48%), β-curcumene (5.81%), E-β-farnesene (2.35%), α-zingiberene (2.18%) and α-cedrene (1.94). Thirty-nine components were identified in the oil of leaves, making up 87.7% of the total composition. The major constituents of the essential oils of the leaves were β-eudesmol (62.04%), β-curcumene (3.43%), ar-curcumene (2.20%) and linalool (2.03%). In particular, both oils were characterized by a high content of β-eudesmol. +PRACTICAL APPLICATIONS: Some species of Phlomis are used as tonic and stimulant in Turkey and against diseases of the respiratory tract or externally for the treatment of wounds. Also, many studies have shown various biological activities such as immunosuppressive free radical scavenging, antimicrobial and antimutagenic activities. © 2010 Wiley Periodicals, Inc.