OBJECTIVE Commiphora gileadensis is a plant in the Burseraceae family that grows in the western area of Saudi Arabia. Traditionally, it is used in the treatment of some superficial infections. METHODS The methanolic extract of Commiphora gileadensis isolated from its leaves and branches. The in vitro study was conducted to determine the effect of this extract on Methicillin-Resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa using an agar diffusion and Minimum inhibitory concentration (MIC) methods. The in vivo study was conducted through two different methods. The first method, 20 male Balb c-1 mice were used for the determination of Commiphora gileadensis methanolic extract toxicity (LD50). In the second method, 40 male mice were used and were put into four groups. The first and second groups were injected subcutaneously with 108 CFU of MRSA 1 mL-1, while the third and fourth groups were injected with 108 CFU of Pseudomonas aeruginosa 1 mL-1. The comparison between groups was done by using a t-test (p<0.05). RESULTS The methanolic extract of Commiphora gileadensis had a greater sensitivity zone on MRSA and Pseudomonas aeruginosa, 7 and 3 mm respectively. The MIC of the extract was 1/8 and 1/2 for MRSA and Pseudomonas aeruginosa respectively. The in vivo study showed that the extract was non-toxic, it also showed that the extract decreased the mortality of mice induced by MRSA injection significantly (p<0.05) While insignificantly with Pseudomonas aeruginosa. CONCLUSIONS The total Commiphora gileadensis methanolic extract had an antibacterial effect on MRSA and Pseudomonas aeruginosa. This extract was non-toxic for the mice.