Four Potato cultivars (Lady Rosetta, Diamante, Gold and Santana) were treated with 20 Gray of gamma rays then screened for salt tolerance by application of 2270 ppm of NaCl in vitro. Evaluation of tolerant mutants was done by biochemical and molecular analysis. Results showed that, Ch.a and b were increased in gamma treated-plantlets compared to control and the highest values of Ch.a was found in Lady Rosetta, Diamante and Santana cvs, while ch.b  as well as Chl. a+b were highest in Diamante and Santana cvs. Phenolics and Carotenoids concentrations were also increased in plantlets as a result of gamma application especially in Santana and Lady Rosetta cvs., respectively. Free amino acids concentration had variable effect between gamma treated and non-treated plantlets, so it increased in Santana and Gold cvs., it decreased in Lady Rosetta and Diamante cvs. Superoxide dismutase and Catalase activity were also increased in all gamma-treated cultivars especially in Lady Rosetta, Diamante and Gold cvs. SDS-PAGE of protein revealed that, gamma-treated and untreated plantlets expressed about 14 to 17 protein bands. Gamma-treated plantlets of Lady Rosetta cv. missing two protein bands with 55 and 6 KDa compared to control, Gamma-treated plantlets of Gold cv. lost three protein bands with 23, 17 and 6 KDa compared to untreated ones while the band with 55 KDa was detected in gamma treated-plantlets. We can conclude that, using of 20-gray gamma rays' dose was more effective tool for induction salt-tolerant mutant plantlets of potato cultivars especially with Santana cv. and such mutants must be re-evaluated on the field experiments.