Populus euphratica is a poplar species famous for its ability to cope with high salinity. Moreover, its distribution area comprises deserts with very hot and dry summers. All species of genus Populus are known to be rather drought sensitive and P. euphratica may grow in such dry areas due to its phreatophytic habit. In this experiment, we studied the ecophysiological and transcriptomal responses of P. euphratica to an increasing drought stress. The drought stress was applied for 6 weeks. Growth and physiological parameters were recorded at different stress intensities and root and leaf tissues were harvested for transcriptome analysis. To identify the molecular mechanisms of stress tolerance in P. euphratica we have sequenced ESTs from several normalized control cDNA libraries and stress enriched subtracted libraries. From this selection of 14000 ESTs about 8100 ESTs were re-amplified and spotted onto DNA microarrays. The DNA microarrays were used in a drought experiment, in a salt experiment and in comparison of natural sites. In common with the other P. euphratica microarray experiments, very few genes (~50) were regulated by drought. An EST database with the P. euphratica ESTs including annotative attributes can be viewed at http://sputnik.btk.fi.