Abstract The transfer of 131I and 137Cs, released after the Chernobyl accident, into domestic animals was studied experimentally in order to determine transfer coefficients from feed into animal products under realistic conditions. The 137Cs transfer coefficients for meat were calculated to be: 0.01 d/kg beef (cow), 0.038 d/kg beef (heifer), 0.038 d/kg beef (bull), 0.35 d/kg veal, 0.4 d/kg pork, 0.33 d/kg sheep, 0.28 d/kg fallow deer and 1.3 d/kg chicken. The transfer coefficients for cow's milk were calculated to be 0.007 d/1 ( 131I) and 0.003 d/1 ( 137Cs), and for sheep's milk 0.06 d/1 ( 137Cs). In egg-white and yolk transfer coefficients for 137Cs of 0.2 and 0.1 d/kg, respectively, could be determined. Biological half-lives and the influence of feed additives on the activity concentrations in meat and animal products are described.