The essential oil from the leaves of Ruilopezia bracteosa was obtained by hydrodistillation, and analyzed by GC-MS. Eighteen components, which made up 99.6% of the oil were identified, the most abundant being β-myrcene (34.2%), α-pinene (24.3%), 7-epi--selinene (9.1%), β-pinene (8.5%) and 6,9-guaiadiene (4.4%). Antibacterial activity was tested against Gram-positive and Gram-negative bacteria using broth microdilution and disk agar diffusion methods. MIC values found presented significant differences between both methods, which may be due to diffusion factors.