en Radiation Biology Radiation Biology تحقيق بديع Original Research <span style="font-weight: bold"> Background:</span> Knowledge of radioactivity levels in human diet is of particular concern for the estimation of possible radiological hazards to human health. However, very few surveys of radioactivity in food have been conducted in Iran therefore the baseline values of the natural radionuclides concentration (40K, 226Ra and 232Th), and man made radionuclide, 137Cs, were determined in twenty six samples of imported foodstuff in Iran. <span style="font-weight: bold">Materials and methods: </span>Twenty six samples of different kinds of imported foodstuff were selected for analysis. These samples, after pretreatment and washing (if necessary), were measured by a low level gamma spectrometry system. <span style="font-weight: bold">Results:</span> All samples were found to contain detectable 40K content in range 6.4 to 778.4 Bq.kg-1 fresh weights (fw). 137Cs, 226Ra and 232Th were detectable in most of the samples. The maximum concentration of 40K, 226Ra and 232Th were found in tea sample, equal to 778.4±23.4, 2.9±0.1 and 5.4±0.2 Bq.kg-1 (fw), respectively, where as for 137Cs it was 3.2±0.1 Bq.kg-1 (fw) in milk powder. <span style="font-weight: bold">Conclusion: </span>The concentrations of 40K and 137Cs in different imported foodstuff are comparable with those from the other countries yet 232Th concentration is higher than the reported values. Also, 226Ra results appear to be higher than the reported values in some cases. Natural and man made radionuclides, imported foodstuffs, activity concentration, gamma spectrometry 149 153 http://ijrr.com/browse.php?a_code=A-10-1-216&slc_lang=en&sid=1 T. Hosseini thosseini@aeoi.org.ir 79003194753284600650 79003194753284600650 Yes A.A. Fativand 79003194753284600651 79003194753284600651 No H. Barati 79003194753284600652 79003194753284600652 No M. Karimi 79003194753284600653 79003194753284600653 No