Samsun city which is between the deltas where Yesilirmak and Kizilirmak rivers run out, exists in the middle part of Black Sea's costal way. It is the biggest city of the Black Sea Region in terms of population, industry, trade, natural and cultural wealth. There is no information about radioactivity measurement reported in water samples in the Samsun province so far. For this reason, gross cc and gross activities of 19 different water samples collected from spring, river and tap waters in Samsun were determined. The instrumentation used to count the gross alpha and gross beta activities was an alpha/beta counter of the low background multiple detector type with 10 sample detectors (Berthold LB770). The average activity concentrations were 51.9 mBg/l, 77.8 mBg/l for gross alpha and gross beta in tap water. The obtained results showed that, natural activity concentrations of alpha and beta emitting radionuclides in drinking, spring and river water samples did not exceed WHO recommendations. For all samples the gross activity is always higher than the gross alpha activity. The results obtained in this study indicate that the annual effective doses are below the WHO recommended reference level of 0.1 mSv/y for all water samples. (C) 2011 Elsevier B.V. All rights reserved.