The genus Eucalyptus is composed of hundreds of species with multiple important uses, making it one of the most valuable forest trees around the world. The genetic improvement of Eucalytpus has been studied especially to improve timber production, wood quality and disease resistance. One of the current approaches to improve Eucalyptus tree species is genetic engineering, and it is a common sense that transgenic plants must be submitted to detailed environmental and health risk assessments in order to guarantee their biosafety for future commercial release. This work aimed to characterize and compare the essential oil composition of leaves from genetically engineered (GE) and non-GE Eucalyptus trees of the hybrid E. grandis x E. urophylla employed in cellulose pulp and paper production. Our results allowed us to conclude that no significant differences in the content or chemical composition of leaf essential oils exist between GE and non-GE Eucalyptus trees.