To study the antimicrobial activity and phytochemicals of extracts from 5 different medicinal plants, as well as to evaluate the synergistic activity of potent plant extracts with suitable antibiotic discs and antibiotics susceptibility of tested microorganisms. The antimicrobial activities of different extracts were evaluated by using agar well diffusion method and antibiotics susceptibility of five selected microorganisms was tested by using disc diffusion method. For determination of synergistic activities of the potent plant extracts along with antibiotic discs, agar well diffusion and disc diffusion methods were combinedly used. In the present investigation, the maximum in vitro inhibition of tested microorganisms, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Staphylococcus aureus was recorded in chloroform and methanol extracts of Terminalia arjuna, ethanol extract of Camellia sinensis, and petroleum ether extract of Polyalthia longifolia which offered inhibition zone ranged from 11 to 18 mm. The maximum antibacterial efficacy was exhibited by levofloxacin with an inhibition zone of 35 mm against Escherichia coli. The potent plant extracts showed positive synergistic effects against Staphylococcus aureus with lincomycin. The phytochemical analysis of the potent plant extracts revealed the presence of saponin, tannin, protein, carbohydrate, flavonoid, terpenoids and glycosides. According to the present study, Camellia sinensis, Terminalia arjuna and Polyalthia longifolia can be used as a potent source of natural antimicrobial agents by replacing commercially available synthetic drug that may have a large number of side effects.