Essential oils obtained by steam distillation from Thymus, Veronica and Agrimonia plant species were subjected to GC-MS analysis. The essential oil of Thymus sp. have revealed the presence of more than ten components. The in-vitro micro-biological activity of these oils were investigated against some pathogenic bacteria, and the results showed that the essential oil of Thymus sp. have significant antibacterial activities towards the Gram-positive bacteria and less inhibition effect on the Gram-negative test bacteria. However, the essential oil of both Veronica and Agrimonia species has showed no activity on the entire test bacteria used