Our previous studies have shown that thermal Agrostis scabra collected from the thermal sites in Yellow Stone Natioanl Park was more tolerant to heat stress than Agrostis stolonifera (creeping bentgrass). This study was designed to compare their gene expression profiles between these two species using differential display analysis (Delta Differential Display Kit). Total RNA was extracted from leaves exposed to a normal growth temperature (20oC, control) or to 40oC for a week (heat stress) and cDNA was synthesized. Twenty pairs of primers were tested with the cDNAs. Forty-two down regulated and Forty-four up regulated gene fragments were identified in both species. Of the up re-gulated gene fragments, 13 were found only in the thermal species, A. scabra. Sequence analysis of some genes fragments showed that the down-regulated genes are related to electron transport chain in photosystem II. The up-regulated genes are mainly signaling/regulatory components involved in the signaling pathway and gene involved in secondary metabolism. We are currently confirming the different expression of these cloned fragments by RNA blot analysis and RT-PCR.