In the present investigation antimicrobial activity of three different plant essential oils i.e., Thymus vulgaris, Th. serphyllum and Mentha longifolia oils have been evaluated. After bioassays, gram-positive bacteria such as Staphylococcus aureus and Gram-negative bacteria i.e., Escherichia coli and Pseudomonas aeruginosa were found susceptible to most of the essential oils. For screening of antimicrobial susceptibility in each essential oil, both positive and negative controls were set to determine MIC (minimum inhibitory concentration), MBC values (minimum bactericidal concentration) and growth inhibition zone diameters. Among all essential oils Th. vulgaris oil was found to be highly bactericidal, as it has shown lowest MIC and MBC values and high growth inhibition zone diameter in comparison to antibiotics. Present study reveals significantly higher broad-spectrum antibacterial activity in essential oils than antibiotics i.e., penicillin, gentamicin, amoxicillin and nalidix acid.