An experiment was carried out in Viçosa, Brazil to evaluate the influence of plant age (3, 6, 9 and 12 months) on the content and chemical composition of essential oils from lemon grass, using a completely randomized design with three replications. The plants were harvested between 7:00 and 8:30 a.m, and harvesting cut made at 20 cm height from the base of the leaf. The collected material was immediately taken to the laboratory where the leaves were selected, and subsequent determination of moisture content and other chemical analysis done. The essential oil extraction was carried out by hydrodistillation. The identification of the chemical components of the lemon grass volatile oil was performed by gas chromatography and mass spectrometry (GC-MS). The quantification of the chemical composition of essential oils was made by the gas chromatograph in conjunction with a flame ionization detector (GC-FID). Based on the results obtained, it can be concluded that plant age did not influence statistically, the essential oil content extracted from the lemongrass leaves. However this provided significant changes in its chemical composition.