Environmental radiation protection program is important in the effort to limit radiation dose to the public to be as low as reasonably achievable. As water is an important factor of transfer of radionuclide to human, therefore it is important to measure natural radionuclide concentrations in rivers. 20 water samples were collected randomly from the main rivers in Kota Tinggi district. The water samples collected were analysed using ICP-MS technique to determine uranium, thorium and potassium concentration in river water. Radionuclide concentrations obtained were compared with the terrestrial gamma radiation dose rate measured in the area. Significance of the results obtained is discussed.