The effect of a composite antidotal treatment - consisting of a mixture of calcium alginate, ferrihexacyanoferrate(II) and potassium iodide - administered in diet and/or Na3(CaDTPA) administered intraperitoneally on the absorption and the removal of radioactive strontium, caesium, iodine and cerium was investigated in 7-week-old female rats. The animals were on respective treatments for 3 days. The retention of 141Ce, 85Sr, 137Cs and 131I was determined in the whole body, carcass, gut, liver, kidneys and respective critical organs (femur, muscle, thyroid) 6 days after their oral or intraperitoneal administration. In animals which received the antidotal mixture or Na3(CaDTPA) alone, the radionuclide retention was practically the same as in rats which were given the composite treatment [mixture + Na3(CaDTPA)]. This indicates that the efficiency of one treatment was not increased by the other. For 141Ce, Na3(CaDTPA) was an effective antidote, while 85Sr, 137Cs and 131I were reduced by the mixture. It is concluded that the composite treatment might be a quick treatment for choice for reducing mixed fission products retention, especially in cases when identification of exposure is difficult or impossible to make.