Assessment of natural radionuclides (238U, 232Th, and 40K) and terrestrial gamma radiation dose rates (TGRD) in major rivers of Kelantan states, Malaysia were conducted. Measurements were carried out using a portable [NaI(TI)] micro roentgen (µR) survey meter and inductively coupled plasma mass spectrometer (ICP-MS) for in situ TGRD and the activity concentrations of 238U, 232Th, and 40K in water samples, respectively. The mean TGRD was found to be 312.98 nGy h-1 and from water samples analyzed, the mean activity concentrations of 238U, 232Th, and 40K was found to be 13.31 mBq L-1, 4.39 mBq L-1 and 1118.72 mBq L-1 which were about 3 times and slightly higher than the world average values of 5 mBq L-1 and 3 mBq L-1 respectively.