Treatment with the essential oils (oregano or thyme) was more effective in reducing L. monocytogenes population than the use of nisin at 500 IU/g. Sensory shelf life of chicken breast meat samples was ca. 6 days for the uninoculated samples, 8 days for samples treated with nisin and more than 10 days for samples with OEO, TEO, OEO plus nisin, and TEO plus nisin respectively. At the point of sensory rejection, the population of L. monocytogenes counts decreased by 2 (OEO 0.5%), 3.7 (TEO 0.5%), 3.4 (nisin), 4.2 (OEO plus nisin), and 3.7 (TEO plus nisin) log cfu/g.