Lactococcus lactis is a dairy culture bacterium widely used in dairy products which contain salt (NaCl) such as cheese and salted butter. Osmotic conditions generally hinder the growth of both pathogen and desirable bacteria. It has been observed that exposure to an environmental stress can develop resistance to several stresses. Some studies have shown that short UV (UV) light exposure build up resistance to acid, ethanol, hydrogen peroxide and heat induced stress. There are many proteins and low molecular weight compounds that are produced under more than one stress condition which protects the cell. If salt tolerance is enhanced in desirable bacteria they would survive better compared with pathogens in salty environments. The hypothesis was whether salt tolerance of Lactococcus lactis can be enhanced. The objective was to study the influence of UV light and heat shock on salt tolerance of L. lactis. L. lactis R-604 cells were exposed to mild stresses of UV light (245 nm) for 5 min or a heat shock at 50°C for 25 min. A control sample was run without any stress. Samples were transferred to M17 broth with 5 concentrations of NaCl (0, 1, 3, 5 and 7% w/v) and incubated aerobically at 30°C for 5 d. Plating was conducted immediately after inoculation and every 24 h for 5 d in M17 agar with 0.5% of lactose and incubated aerobically at 30°C for 48 h. Three replications were conducted. On d 1 and 2 no differences were observed for either UV light or heat shock treated cells when exposed to 0, 1 and 3% w/v NaCl, however growth inhibition was observed using UV light or heat shock at 7% w/v NaCl. On d 1,2 and 3, resistance to salt was improved using UV light or heat shock treated cells when exposed to 5% w/v NaCl compared with control. On d 5, mild heat shock and UV light exposure had no effect on salt tolerance. Until d 4, different amount of NaCl and days of salt exposure had a differential effect on growth of L. lactis R-604.