Ataturk International Airport (AIA) hosts the most crowded air traffic in Turkey. It is located to the south of the city in an urban area. A new airport is under construction in the north of Istanbul, which is a rural site. All commercial operations of AIA are going to be moved to the new airport after the completion of the construction. Aircraft emissions have adverse impact on ambient air quality, especially at urban sites. In this study, aircraft emissions from LTO cycles were estimated in AIA. NOx, CO, and HC emissions were 4249, 2153, and 181 t year(-1), respectively. Taxi phase was responsible for the vast majority of CO and HC emissions. The majority of NOx emissions occurred from climb phase. Valuation of the emissions was estimated according to their unit damage price. The total damage value was 9,420,848 a,notsign year(-1). NOx contributed more than 99% of the total amount. Dispersion of the pollutants was modeled with EPA's AERMOD. The calculated NOx and CO concentrations at the closest air quality monitoring station to the airport were compared with the observed results. The contribution of aircraft emissions to NOx and CO concentrations at the station was 5.1 and 2.4%, respectively. The annual limit value of NOx was exceeded in most of the airport area and the residential area to the west of the airport. The highest concentration was 566 mu g m(-3), which was estimated at the parking/gate area. The maximum daily 8-h mean concentration of CO exceeded the limit value only at the gates and parking area.