Mentha essential oil is one of the most utilized essential oil in the food and pharmaceutical industries. The present study reports the chemical composition and antibacterial properties of leaf essential oils of Mentha species. Further, the effect of the harvesting period on essential oil yield was also investigated. Firstly, the cultivated Mentha piperita and wild Mentha longifolia, revealed significant differences in their chemical profile. M. longifolia essential oil was characterized with endo-borneol (1.12-6.2%), caryophyllene (2.72-7.03%), isopipertenone (0.07-0.36%), germacrene D (0.98-3.22%), 3-cyclopentene-1-one,2-hydroxy-3-(3-methyl-2-butenyl)- (21.91-56.72%) and piperitone oxide (8.96-39.31%), whereas, M. piperita leaves essential oil was found rich in isomenthone (5.97-6.75%), 1-menthone (7.32-18.32%) and menthol (18.03-58.53%), etc. The essential oils of both Mentha species exhibited strong antimicrobial activity as evaluated using poisoned food technique, dry weight method, and disc diffusion method against Candida albicans, Fusarium oxysporum, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Secondly, the maximum essential oil yield was observed in July month, 0.63±0.01 and 0.56±0.01%, respectively for M. piperita and M. longifolia.