This study presents the measurement results of environmental radioactivity levels for Gaziantep, an industrial and trade centre in the southeastern part of Turkey. The outdoor gamma absorbed dose was measured as 50.1 nGy h(-1), corresponding to a total gamma radiation level (of terrestrial and cosmic origin) of 61.5 mu Sv y(-1). The activity concentrations in the surface soil samples collected from the study area were determined as 25.2, 23.7 and 289.2 Bq kg(-1) for the natural radionuclides (238)U, (232)Th and (40)K, respectively, and 8.02 Bq kg(-1) for the fission product (137)Cs. These natural radioactivity sources result in a terrestrial gamma level of 46.9 mu Sv y(-1). The drinking water samples collected from the region carry an average of 0.0493 Bq l(-1) of gross alpha and 0.1284 Bq l(-1) of gross beta activities, which together cause an annual effective dose of 1.83 mu Sv. The measurement results obtained in this study indicate that the region has a background radiation level that is within the natural limits and shows no significant departure from the other parts of the country.