The evaluation of Iranian rice germplasm for salt tolerance and mapping of the related QTLs were performed in four experiments. In the first experiment, the response of 75 rice cultivars, including Iranian landraces, improved and introduced cultivars, to salt stress was studied at seedling stage in a factorial trail in randomized complete block design with three replications. Cultivars were evaluated at normal condition (1.2 dS.m -1 ) and two salinity (4 and 8 dS.m -1 of NaCl) levels. Significant differences were detected among cultivars and between salinity levels for all the studied traits. Root and shoot length and dry weights, biomass and K + percentage were reduced as the salinity level increased to 8 dS.m -1 , but Na + percentage and Na + / K + ratio were increased. Genotypic code had significant negative correlations with shoot dry weight and biomass, but significant positive correlations with Na + concentration and Na + / K + ratio in 4 and 8 dS.m -1 salinity levels. In 4 dS.m -1 salinity level, shoot dry weight had a high direct effect on genotypic code. In 8 dS.m -1 salinity level, high positive and negative direct effect on genotypic code were found for biomass and Na + concentration, respectively. Stepwise regression analysis indicated the importance of biomass, shoot dry weight and K + concentration in determination of genotypic code variability. Cluster analysis grouped the cultivars in salt tolerant, sensitive and intermediate classes. In the second experiment, biomass variation was studied in greenhouse at normal condition (1.2 dS.m -1 ) and two salinity (4 and 8 dS.m -1 of NaCl) levels. Significant differences were found among genotypes and between salinity levels for biomass at vegetative growth stage. In the third experiment, 65 rice cultivars were evaluated for agronomic traits, yield and yield components in a saline field located near the Someasara city. Grain yield had significant and positive correlations with seed weight/plant, No. of plant/m 2 , plant height, panicle length and biomass at 4 and 8 dS.m -1 salinity levels (from the second experiment). Stepwise regression revealed the importance of seed weight/plant and No. of plant/m 2 in grain yield variability. In the fourth experiment, two tolerant and sensitive cultivars (Tarommahalli and Khazar, respectively) were selected based on the result of previous experiments, and crossed to produce the F 2 population for QTL mapping. Linkage map based on SSR markers was derived using 74 polymorphic markers in 12 linkage groups in parents and 192 F 2 individuals. This map covered 1231.5 cM of the genome. The phenotypic values were collected