It is required to develop the indicators of salt tolerance of the plants, which grows in the salt-accumulated zones of arid regions. In this study, we examined the responses of the stable carbon isotope ratio of leaf organic matter (d¹³C_om) to salt treatment in the saplings of Tamarix ramosissima Ldb., which were grown under glasshouse conditions and supplied with NaCl solution of 0, 200 and 400 mmol/L. We also measured the biomass, the transpiration rate and stomatal conductance of leaves and the NaCl amount in the secretion from salt grants. The d¹³C_om 162 days after the start of salt treatment was higher in the saplings supplied with higher salinity water. This result suggests that the d¹³C_om would be available as an indicator of salt tolerance of T. ramosissima grown under the controlled conditions. We examined the responses of the d¹³C_om in some halophytes, which grow in the salt-accumulated desert in Xinxiang, China. The cation concentrations in the soil, leaves, stems and roots were also measured for five halophytes. Significant relations were not found between the soil salinity and the d¹³C_om. Further discussion will be presented in the poster.