The activity concentrations and absorbed gamma dose rates due to primordial radionuclides and Cs-137 have been ascertained in 222 soil samples in 18 counties of the Trabzon province of Turkey using a HPGe detector. The mean activity concentrations of U-238, Th-232, K-40 and Cs-137 in soil samples were 41, 35, 437 and 21 Bq kg(-1), respectively. Based on the measured concentrations of these radionuclides, the mean absorbed gamma dose in air was calculated as 59 nGy h(-1) and hence, the mean annual effective dose due to terrestrial gamma radiation was calculated as 72 mu Sv y(-1). In addition, outdoor in situ gamma dose rate (D) measurements were performed in the same 222 locations using a portable Nal detector and the annual effective dose was calculated to be 66 mu Sv y(-1) from these results. The results presented in this study are compared with other parts of Turkey. Radiological maps of the Trabzon province were composed using the results obtained from the study. (C) 2011 Elsevier Ltd. All rights reserved.