This study was concerned with the measurement of natural and artificial radionuclides in soil samples and indoor radon concentrations in the Samsun province, Turkey. In soil samples, the values of individual mean activity of Ra-226, Th-232, K-40 and Cs-137 radionuclides were found to be 31, 22, 341 and 16 Bq kg(1), respectively. The radiological parameters, such as the absorbed dose rate in air, the annual effective dose (AED) and excess lifetime cancer risk, were calculated. Indoor radon measurements were carried out with CR-39-based radon dosemeters at 127 dwellings in the Samsun province. The mean annual Rn-222 activity was found to be 106 Bq m(3) (equivalent to an AED of 1.88 mSv). The seasonal variation of Rn-222 activity shows that maximum levels are observed in the winter, while minimum levels are observed in the summer. The mean lifetime fatality risk for the studied area was estimated at 1.4510(4). The results obtained did not significantly differ from those obtained in other parts of the country.