In this study, gamma activity concentrations of U-238, Th-232 and K-40 in surface soil and Rn-222 concentrations in dwellings of Zonguldak were measured. In order to measure gamma activity a gamma spectrometry (ORTEC-905-4) with a high-sensitivity NaI (Tl) detector was used. Radon concentration measurements were made by the CR-39 nuclear track detectors. The measured activity concentrations of U-238, Th-232 and K-40 were found to be between 10-145, 23-91 and 215-755 Bqkg(-1) with the averages of 40.7, 38.7 and 470.0 Bqkg(-1), respectively. Radon concentrations were found to be from 27 to 234.5 Bq m(-3) with the average of 68.6 Bq m(-3).