Abstract Two methods (agar diffusion and broth microdilution) were used to assess the antibacterial activity of Origanum majorana L. oil of Tunisian origin against 10 bacteria. The results showed that this oil was active against all of the tested strains. The most susceptible were Escherichia coli, Streptococcus A, Shigella dysenteria and Salmonella enteritidis. The least susceptible one was Pseudomonas aeruginosa.