The essential oils from six chemo-types of Zataria multiflora (ZMO) was obtained and examined for chemical composition and antioxidant, antimicrobial and cytotoxic activities. Chemical analysis of ZMO was done by using gas chromatography and mass spectrometry (GC/MS). The antioxidant capacity of ZMO was examined through measuring ABTS, H2O2, nitrite and malondialdehyde (MDA) scavenging effects. The antibacterial activity toward Salmonella typhimurium, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Aspergillus niger and Candida albicans were tested by minimum inhibitory concentration (MIC) determination. The cytotoxic effect of ZMO was tested on the human nasopharyngeal cancer cell line (KB), liver hepatocellular carcinoma cell line (HepG-2) and epithelial breast cancer cell line (MCF-7). The main components of ZMO were carvacrol (4â57%), thymol (1â45%), p-cymene (4â20%), Î³-terpinene (1â38%) and linalool (1â33%). ZMO exhibited good antioxidant activity against ABTS, H2O2, nitrite and MDA at concentrations less than 10 Î¼g/mL. ZMO showed good cytotoxic activity against tested bacteria and fungi, and tumor cell line at concentrations less than 10 and 20 Î¼g/mL, respectively. Thymol-rich ZMO exhibited stronger antioxidant activity, while carvacrol-rich ZMO exhibited stronger antibacterial, antifungal and antitumor activities.