The concept of the"Ecological Footprint"(EF) is used to quantify the ecological sustainability of human development.It permitsest imation of the pressure and impact of human activities on ecosystems. The EF can be applied to urban ecological studies

to determine the impacts of concent rated human set tlement. This study calculated the EF of Xi'an in 2001 and compared the result with the EF of a few other countries and regions. The EF of the Xi'an area was estimated at 1.0 ha per person. The ecological carrying capacity of the Xi'an area is calculated to be 0. 13 ha per person. Therefore

the EF of the Xi'an area is 7. 9 times the area's ecological carry ing capacity.The EF of Xi'an City is 1.3 ha per person

which is 9.75 times more than the city's ecological carrying capacity.The EF of Xi'an City is slightly higher than the average EF of China

but it is lower than that of some other countries and regions.The results support an argument that EF increases with higher levels of development. The results similarly support an argument that Xi'an is relat ively underdeveloped. The need for further economic development should be balanced with improved ecological conditions and reduced development impact in order to ensure the sustainability of Xi'an city and region.