Salinity is a major environmental constraint limiting crop yields in semi-arid and arid regions. The improvement of salt tolerance is one approach to utilize saline soils or abundant saline water supplies. In Triticeae plants, salt tolerance is believed to be associated with sodium ion exclusion (Greenway & Munns, 1980) including barley which is regarded as the most salt tolerant of the cereals (Maas, 1987). Barley cultivar Maythorpe and its derived mutant Golden Promise differ in salt tolerance (Forster et al., 1994). The difference between these two genotypes has been attributed to the ability of Golden Promise to prevent accumulation of sodium ion in its shoot under saline conditions. We employed the Barley1 GeneChip from Affymetrix to monitor the transcriptome of Maythorpe and Golden Promise under control and salinity stress conditions. Plants were grown in a hydroponic system. Salinity stress (150 mM NaCl, maintaining a Na: Ca ratio of 10:1) was induced when the plants were 16 days old. Root and shoot tissue from 25 day old plants growing in control and stress conditions were used for expression profiling. This work is part of a collaborative effort between International Rice Research Institute, UC-Riverside and U.S. Salinity Laboratory (USDA-ARS) to use the global gene expression for exploring the parallels which may exist in response of barley and rice to salinity stress.