This paper describes the changes occurred in the internal structure of central part of Ulaanbaatar, the capital city of Mongolia, since the fall of communism in Mongolia. Currently, Ulaanbaatar is encountering increasing urban development problems, similar to many cities in developing countries. In the city, different problems had been accumulated during the communist era. These problems have been accelerated by the reforms of the entire political and economic systems, unregulated market development and the rapid population growth caused by migration from rural areas. Actually, in the country there are missing urban-oriented research and surveys as well as thoroughly conducted and creative activities, based on the modern urban geographical theory and methodologies used in the developed countries. One of the methods that can be used for this purpose could be the application of the modern remote sensing (RS) and geographical information system (GIS) techniques and technologies for rapid urban-related planning and
management. In this study, we wanted to detect the changes occurred in between 1990 and 2002 in the central part of Ulaanbaatar city using RS and GIS techniques. For this purpose, the urban land use has been selected within the city business district (CBD) area of the capital city and for the urban change detection historical GIS data, SPOT 5 and Quickbird images of 2002 have been used. The analysis was carried out using the Erdas Imagine 8.6 installed in a PC environment.