Lemon balm (Melissa officinalis L.) has been employed for medicinal use for its volatile oils and other components in western countries. The compositions or effective components can be influenced by climate, cultivation practice and varieties. Essential oil obtained by steam distillation were analyzed by gas chromatography-mass spectrometry (GC/MS). Thirty-three components were identified. Terpenoid is the main component of the essential oil, in which citral (citral = neral + geranial) takes up nearly 54%.