IN VITRO grown potato cultivars shoots were used to understand….. how polyvinyl pyrrolidone (PVP) and three levels of potassiuminteract with two levels of salinity to determine Na+ and K+ contents,and antioxidant enzyme activities leading to control survival,multiplication and growth of cultured plant shoots. Explant survivaland the number of regenerants/explant decreased with the increase of NaClconcentration but increased K+ content of the culture medium from 20mM to 30 mM improved explants survival frequency and the growthparameters estimated under relatively high salt stress (80 mM NaCl) inboth cultivars. Also, number of regenerants was influenced by K+ levelwhere it was higher in medium containing 40 mM NaCl and 30 mMK+ than other cultured on the same NaCl concentration with 20 mMK+. The positive effect of 30 mM K+ on the previous parameters wasassociated with increase shoot K+ content leading to decrease Na+/K+ratio and increase of some antioxidant enzymes (SOD, POX and CATin Agria or SOD, POX and APX in Hermes) activity, especially underrelatively high salt stress. PVP application increased K+ content andactivities of some antioxidant enzymes (CAT and APX) but decreasedNa+/K+ ratio of shoots subjected to relatively high salt stress in Agriabut under both salt stresses in Hermes. Consequently, sufficientpotassium supply was necessary to conserve low Na+/K+ ratio andefficient scavenging system by antioxidant agent (PVP) application orincrease the endogenous antioxidant enzymes activities leading tominimize the negative effect of salt stress on in vitro grown potato.