The concentrations and distribution of natural and artificial radionuclides in sediment and water samples collected from Fiirtina River in the Eastern Black Sea region of Turkey were investigated with an aim of evaluating the environmental radioactivity and radiation hazard. Natural gross alpha and gross beta activities were determined for 21 different water samples, and the activity concentrations were obtained for Ra-226, Pb-214, Bi-214, Ac-228, Tl-208, K-40 and Cs-137 in 20 different sediment samples. The obtained results showed that natural gross alpha and gross beta activity concentrations in water samples range from 12.4 +/- 3.4 to 66.2 +/- 9.2 mBq l(-1) and from 27.9 +/- 3.3 to 133.3 +/- 4.1 mBq l(-1), respectively. The mean activity concentrations were 32.6 +/- 3.8 mBq l(-1) for gross alpha and 69.9 +/- 4.4 mBq l(-1) for gross beta. Generally, the gross beta activities were higher than the corresponding gross alpha activities. The average concentrations of U-238 and Th-232 daughter products vary from 11 to 167 Bq kg(-1) and from 16 to 107 Bq kg(-1), respectively. The concentrations of K-40 and 137Cs vary from 51 to 1,605 Bq kg(-1) and from 0.8 to 42 Bq kg(-1), respectively. Sediment characterization was also investigated using grain size, thin section and XRD analysis.