The aim of this study is to investigate for the first time the chemical composition of the essential oil extracted from Mentha piperita cultivated in Ouargla, Algeria. The other objective is to determine the antioxidant and antibacterial activities against certain bacterial strains in order to find new metabolite products, which are characterized by a biological activity. Twenty-three compounds were identified representing 99.99% of the total oil. The principal components are: Carvone (51.04%), Limonene (36.37%) and β-Pinene (1.66%), which compose 89.07% of the oil. The antimicrobial activity of oil was tested using the diffusion method by determining the inhibition zone and the minimal inhibitory concentration. The results showed a great potential of antimicrobial activity against the bacterial strains with very high degree of sensitivity of E. coli Gram-negative strains than other bacterial tested. Furthermore, the essential oil was tested for its antioxidant activity using the 2,2-diphenyl-l-1-picrylhydrazyl (DPPH) radical-scavenging and Ferric Reducing Power (FRAP) methods. The result showed a considerable level of antioxidant activities of the essential oil investigated with (IC 50 = 32.94 µg mLG 1 ) lower than synthetic antioxidant agents ascorbic acid for DPPH method and higher than synthetic antioxidant agents for Ferric reducing power method with EC 50 value of 48,76 µg mLG 1 .