The present study was designed to investigate the chemical composition of four medicinal plants essential oils, studying and evaluation the antioxidant and antimicrobial activity of oils, the oils under study were lemon grass (Cymbopogon citratus) belong to family (Poaceae), origanum (Origanum Majorana) belong to family (Lamiaceae), thyme (Thymus Vulgaris) belong to family (Lamiaceae), and rosemary (Rosmarinus officinalis) belong to family (Lamiaceae). The major compounds found in lemon grass, origanum, thyme and rosemary essential oils, were D-Limonene 54.01%, terpinene 4-ol 36.06%, thymol 48.06% and 1,8-Cineole 32.5% respectively. The antimicrobial activity of the investigated essential oils were tested against six bacterial (three gram +ve bacteria and three gram -ve bacteria) and two fungal strains including gram positive (S. aureus, B. subtilis and B. cereus), gram negative (E. Coli , S. typhimurium and Proteus sp) and two fungal (Candida albicans  and Aspergillus niger). The antioxidant potential of lemon grass, orignaum, thyme and Rosemary essential oils were further highlighted by the quenching of DPPH free radicals. lemon grass essential oil showed the strongest radical-scavenging effect (69.97%) at 50 g/L.