Two constrasting populations of seabuckthorn (Hippophae rhamnoides L.) from western China were employed to study there differences in adaptive responses to drought . The Daofu population was from a wetter upland climate region ,whereas the Dingxi populations was from a drier lowland climate region . A completely randomized design with two factors ,tweo populations and two watering regimes (100% and 25% of the soil water holding capacity) ,was used . In both populations , drought significantly decreased growth and the net photosynthesis rate (A) , and significantly increased the root/shoot ratio (RS) ,catalase (CAT) ,peroxidase (POD) , glutathione peroxidase (GPX) and ascorbate peroxidase (APX) activities , and abscisic acid (ABA) and proline contents . Compared with the Daofu population , drought induced a greater RS value , higher CAT , GPX , and APX activities ,and a higher ABA content in the Dingxi population , whereas the gas exchange traits ,for exanple the stomatal limitation value (Ls) and intercellular CO2 concentration (Ci) , were less responsive to drought in the Dingxi population .The two pupulations may have developed different stratergies to tolerate drought , such as different pathways to dissipate excess absorbed light energy , to resist oxidative stress , and to keep water status . Such factors enable the Dingxi population to tolerate drought batter than the Daofu population .