Abstract: Cold-regulated proteins (CORPs) are induced by cold and thus closely related with cold tolerance. Most cold-induced genes may respond to water stress. We used RT-PCR to confirm that cold-induced siCOR in Sasussured involucrata was also induced by water stress. To investigate the possible role of S. involucrata siCOR in drought tolerance, we performed the drought-tolerance analysis using siCOR transgenic tobacco. Compared with untransformed wild-type (WT) plants, transgenic lines had greener leaves and more roots. Water stress experiments showed transgenic lines with delayed and slightly wilted leaves, but they recovered faster and more completely after rewatering as compared with WT plants. Transgenic lines also showed lower reduction of relative water content and relative quantum yield of PSII and smaller increase of relative conductivity and malondialdehyde content as compared with WT plants. Under drought stress simulated with PEG6000 treatment, transgenic T3 seeds showed higher germination rate and reduced inhibition of main root growth than WT. These results suggested that siCOR may play an important role in drought stress.