Salt stress is one of the main factors disturbing the physiology of organisms, including epigeic lichens inhabiting roadsides, due to de-icing salts used in winter seasons. The aim of the research was to study the effect of acute salt stress in various doses on the chlorophyll fluorescence parameters of chlorolichens, i.e., Cladonia furcata, C. mitis, Diposchistes muscorum, and cyanolichens, i.e., Peltigera didactyla, and P. rufescens, which naturally grow inland in the vicinity of roads. We also aimed to study changes in the photosynthetic efficiency of lichens over time and their responses to rainfall simulations in the days following exposure to salt stress to test whether liquid water supply improves photosynthetic efficiency. Salt stress led to a reduction of it in cyanolichens in most experimental groups, while in chlorolichens only treatment with 2.9-3.9M NaCl solutions significantly decreased F_V/F_M. Exposure to acute salt stress significantly affected fluorescence transient curves in all studied species. With respect to chlorolichens, a marked decrease of FM was observed and the flattened shape of the transient curves after treatment with the highest salt doses was the most apparent. Significantly greater disturbances were observed in cyanolichens in which the induction curve lost its sigmoid characteristics after treatment with solutions with a concentration greater than 0.35M. Furthermore, in all lichen species, increased values of ABS/RC and DI ₀/RC and decreases in PI _ABS, ET ₀/RC and TR0/RC as well as quantum yields and efficiencies were observed. Simulated rainfall resulted in a significant increase in the photosynthetic efficiency of chlorolichens to a level corresponding to healthy lichens almost throughout the duration of the whole experiment. On the contrary, in the case of cyanolichens, significant increases in F_V/F_M after water treatment were found only after exposure to low salt doses and, at the latest, 24 h after the stress. Although many cyanobacteria developed adaptations to survive in highly saline environments, cyanobionts present in inland lichen species seem to be highly susceptible to salt stress. We concluded that the time when rainfall occurs after exposure to salt stress is a crucial factor affecting the potential regeneration of PSII efficiency. Regeneration after rainfall is an important aspect for epigeic lichens occurring near roadsides, where, during the winter season, they are exposed to de-icing salt for a long time, and rainfall may partially compensate for their disturbances and increase their photosynthetic efficiency, enhancing the possibility of survival.