The essential oil of Fumaria Vaillantii Loisel was isolated by hydrodistillation using a Clevenger-type apparatus. In order to, identification of chemical composition, the obtained essential oil was injected to GC/MS instrument. Thirty six components were identified, the major components more than 1 percent include: trans anethole (14.97%), 1,8-cineole (13.01%), menthole (9.34 %), menthone (5.18%), beta-inone (5.02%), cyclopentadecanolide (4.53%), myristicine (3.67%), alpha-pinene (3.58%), thymole (3.19 %) and isomenthone(3.14% ). In this study also we evaluated the antibacterial activity of essential oil of Fumaria vaillantii Loisel against the growth of clinical isolates of Staphylococcus aureus and Escherichia coli using agar disc diffusion method. The results showed that the antibacterial activity of the essential oil was well.