A set of measurements have been conducted in order to determine the annual effective dose resulting from the ingestion of natural radionuclides present in eight different brands of bottled water commercialised in Tunisia. Using high-resolution gamma spectrometry technique, we have noted the presence of the following radionuclides: 214Bi, 226Ra, 228Ac, 212Pb, 235U and 40K. For all classes of age, only the radium concentration was found to be significant in the calculation of the equivalent dose. Some of the studied samples exceeded the reference level of 0.1 mSv y(-1) of effective dose.