Abstract: The essential oil composition of Pistacia lentiscus, Pistacia vera and Pistacia terebinthus was analyzed by GC and GC-MS analysis and their antifungal activity was studied against ten phyto-pathogenic fungi. Qualitative and quantitative differences between oils were observed. All oils were rich in monoterpene hydrocarbons, the major constituents were α-pinene (16-20%), α-terpinene (32-41%) and limonene (4-25%). Principal component analysis and hierarchical cluster analysis separated the three Pistacia leaf essential oils into two groups, each constituting a chemotype. The in vitro antifungal activity of tested oils has shown a significant antifungal activity against all tested fungi.