Salt stress is one of major restrictions for the production of lettuce. In order to identify promising lettuce genotypes having tolerance against salt stress, effect of different sodium chloride (NaCl) concentrations (0, 100, and 200 mM) on electrolyte leakage and growth of thirty-two lettuce landraces from Korea was evaluated. Screening salt tolerant genotypes based on cluster analysis using data of electrolyte leakage discriminated 'IT105183' and 'IT195057' as the most salt tolerant landraces. More importantly, salinity significantly reduced growth of lettuce, but the reduction rates of growth caused by salt stress in salt-tolerant genotypes were much smaller than those in salt-sensitive genotypes. These results indicate that 'IT105183' and 'IT195057' have high potential for being used as parents to improve salt tolerance in other lettuce cultivars.