Six cultivars of potato (Solanum tuberosum L.) Bartina, Spunta, Cardinal, Desirée, Timate and Fabula were assayed in vitro for salinity (NaCl) tolerance. A modified single-node cuttiang bioassay was used in which cultivars were exposed to a range of NaCl levels (0, 40, 80 and 120 Mm), in a Murashige and Skoog medium, for 1 month. Evaluations were performed twice for each cultivar at each salt level. Six vegetative growth parameters (shoot and root length, fresh and dry weights) were measured at the time of harvest and corrected for differences in cultivar vigor. Fresh weight of shoot and length of shoot decreased by given range levels of NaCl. The effect of all treatments was very drastic on length and weight of root. The cultivar Bartina exhibited greater tolerance to the highest salt doses. Plants of this cultivar had greater shoot length than other cultivars at all salt concentrations tested. The results indicated that cultivar "Bartina" is more salt tolerant than other cultivars studied.