The vertical distribution of Ra-226 and Po-210 was investigated in the cultivated soils of the Buyuk Menderes Basin in Turkey. Five soil cores down to a depth of about 50 cm were taken from each site and divided into strata of 2-3 cm intervals. The samples were analyzed for their Ra-226 and Po-210 activity concentrations using radioanalytical methods. Down-core concentration profiles of Ra-226 and Po-210 in the soil cores from five sites are obtained. The activity concentrations of soil cores range from 80 to 1170 Bq kg(-1) for Ra-226 and from 10 to 870 Bq kg(-1) for Po-210 with the depth. Analysis of the vertical soil profiles indicate that the activity concentrations of Ra-226 and Po-210 for soil strata at all the sites have not extremely changed with depth. (c) 2008 Elsevier B.V. All rights reserved.