Listeria monocytogenes is a food-borne pathogen responsible for the disease listeriosis and is commonly isolated from dairy products and facilities. Most strains of the same sequence type (ST) contain highly conserved plasmids, though little is known of the contributions of plasmids on survival in dairy foods and environments. To determine the contribution of plasmids to survival under such conditions, we studied 3 L. monocytogenes ST5, ST8, and ST121 strains, which were isolated from dairy foods and production facilities, and contain plasmids ranging from 62.2 to 90.5 kb harboring putative stress response genes. Plasmid curing was conducted by exposure to subinhibitory novobiocin concentrations (0.3 µg/ml) in tryptic soy broth + yeast extract at 44°C. Wildtype (wt) and plasmid-cured (Δ) strains were exposed to sublethal concentrations of oxidative stress (H₂O₂), salt (NaCl), acid (lactic acid), heat stress, or disinfectant (benzalkonium chloride, BC) for 2 h at 20°C. After stress exposure, cells were plated on tryptic soy agar for colony forming unit (cfu) counts. When exposed to 0.01% H₂O₂, 15% wt/vol NaCl with pH 5, or 1% vol/vol lactic acid, cfu counts for all wt strains were significantly higher (P < 0.001, P < 0.05, and P < 0.001 respectively) than those of the Δ strains. cfu counts for the ST5 wt strain exposed to 10 µg/mL BC were significantly higher (P < 0.001) than the Δ strain. The ST8 and ST5 wt strains exposed to an elevated temperature (50° and 55°C respectively) had a significantly higher (P < 0.01 and P < 0.001) cfu count than the Δ strains. Our data revealed that L. monocytogenes ST5, ST8, and ST121 plasmids confer increased tolerance against elevated temperature, salinity, acidic environments, oxidative stress and disinfectants. Further examination of the phenotypic and functional characteristics of plasmids is required to better understand the mechanisms used by L. monocytogenes for survival in dairy food and food production facilities.