The content of heat shock proteins in tissue of potatoes of two cultivars (Lugovskoy and Lukyanovsky) infected with the ring rot disease causative agent Clavibacter michiganensis ssp. sepedonicus and treated with heat shock (39 °C, 2 h) was investigated. The synthesis of HSP101 and HSP17.6 in potato plants of the two cultivars wasn't revealed in control conditions. The ability of infected plants to synthesize HSPs in response to heat stress was non-specific. Heat shock of 39 °C induced the synthesis of HSPs in tissues in both potato cultivars. The infection lightly induced the synthesis of HSPs in potato plants of cultivar Lukyanovsky, and there were no HSP observed in plants of cultivar Lugovsky. This may be attributed to different dynamics of HSP levels in plants of these two cultivars. For the identification of preadaptation of potato plants to biotic stress, plants at first were treated by heat shock (39 °C, 2 h), then were infected by the pathogen, and at last 2 days later the content of HSPs was identified. The fact that the high content of HSPs was observed in potato tissues 2 days later after heat stress effect is of interest. The infection of potato plants of cultivar Lugovsky following the heat stress reduced their ability to synthesize HSP60 and HSP17,6 in comparison to non-infected plants treated by heat. However, the increase in content of HSP101 in tissues of the infected and heat-treated plants in comparison to the content of HSPs in tissues of plants which were infected and treated by heat was observed.