en Medical Physics Medical Physics تحقيق بديع Original Research <span style="font-weight: bold">Background: </span>The sources of radioactivity in the environment have natural, terrestrial and extraterrestrial, and anthropogenic origins. Plants may get radioactive nuclides in two ways: (i) by the deposition of radioactive fallout, (ii) by absorption from the soil. <span style="font-weight: bold">Materials and Methods: </span>The Concentrations of the natural radionuclides (226Ra, 228Ra, 40K) and the artificial radionuclide (137Cs) in leek and parsley in Tehran province-Iran were determined using HPGe. Also the effective dose due to the ingestion of such vegetables by the population of Tehran province was studied. <span style="font-weight: bold">Results:</span> The average value of radionuclide concentrations in parsley samples were measured 177.69 ± 12.47 mBq kg-1 fresh for 226Ra 349.62 ± 28.42 mBq kg-1 fresh for 228Ra 187364.6 mBq kg-1 fresh for 40K. The average value of radionuclide concentrations in leek samples were measured 94.31 ± 6.46 mBq kg-1 fresh for 226Ra 207.47 ± 19.46 mBq kg-1 fresh for 228Ra 174555 ± 1704.21 mBq kg-1 fresh for 40K. The concentrations of 137Cs in most of Parsley and Leek samples were below the minimum detectable activity (MDA). <span style="font-weight: bold">Conclusion:</span> The Average 226Ra and 228Ra activities in 29 leek and parsley samples were about 2.63 and 6.78 times the reference values, respectively. The annual effective dose resulting from the studied radionuclides for the adult population in Tehran province were found to be safe in comparison with normal background areas. Iran. J. Radiat. Res., 2010 8 (2): 103-110 226Ra, 228Ra, 40K, 137Cs, leafy vegetable, HPGe, effective dose. 103 110 http://ijrr.com/browse.php?a_code=A-10-1-357&slc_lang=en&sid=1 V. Changizi changizi@sina.tums.ac.ir 790031947532846001824 790031947532846001824 Yes Z. Jafarpoor 790031947532846001964 790031947532846001964 No M. Naseri 790031947532846001965 790031947532846001965 No