The chemical composition of the essential oil extracted from the dried aerial parts of Thymus zygis harvested from the Khenifra region (central Middle Atlas of Morocco) was studied by gas chromatography coupled with mass spectrometry (CPG and CPG / MS). Fifty-four (54) constituents, representing (99.98%) of the essential oil have been identified. The majority compounds are: Linalool (4.79%), Camphene (4.00%), Thymol (38.59%), Carvacrol (4.69%), o-cymene (19.11%) and β-E- ocimene (10.20%) with a total percentage of 81.38%. The insecticidal activity was achieved against Aphis fabae. This preliminary study showed that the essential oil of Thymus zygis has a high toxicity towards this insect. The results of the tests showed a very important activity during 24 hours of the treatments confirmed by the values of LD50 and LD90. This activity was probably due to its major constituents. The antibacterial activity was studied in vitro against gram-positive bacteria, Bacillus subtilis (CECT 498) and Staphylococcus aureus (CECT 240), gram-negative bacteria, Escherichia coli (CECT 516), and Micrococcus luteus (CECT 244). The results of the tests helped to quantitatively assess the antibacterial activity by searching for minimum inhibitory concentrations of MIC and minimum bactericidal concentrations of CMB, which have a variable activity depending on the strain tested. The study of the antioxidant activity of Thymus zygis oil compared with the usual antioxidants α-tocopherol and ascorbic acid showed that this oil has an antioxidant effect.