Abstract: OBJECTIVE The chemical composition, antimicrobial activity and inhibitory effect to cell proliferation of the essential oil from Ruta graveolens were studied. METHODS The chemical composition of the essential oil obtained by hydrodistillation from Ruta graveolens was analysed by GC-MS. The antimicrobial activity of the oil was evaluated against 9 micro-organisms using agar disc diffusion method. The inhibitory effect of the oil to cell proliferation was evaluated on HepG2 and NCI-H460 cell lines by MTT assay. RESULTS Twenty-one components were identified in the oil, and main compounds of the oil were 2-Undecanone (46.15%), 2-Nonanone (27.01%) and 2-Acetoxytridecane(12.73%). The oil presented a broad antimicrobial spectrum, and exerted strong bactericidal activity agains Staphylococcus aureus CCTCC 26001, Staphylococcus albus CCTCC 26101, Staphylococcus epidermidis CCTCC 26069 and β-hemolytic streptococcus CCTCC 32210. The data of MTT test indicated that the oil could exert an anti-tumor activity, especially more active for 48 h incubation than 24 h against two cancer cell lines. The IC₅₀ values of 23.21 μg·mL^-1 and 21.87 μg·mL^-1 were measured for HepG2 and NCI-H460 carcinoma cell lines, respectively. CONCLUSION Our study suggests that the essential oil of Ruta graveolens could be one of potential medicinal resources for antibacterial and antitumor agents.