[en] Following both single and repeated oral doses of cesium-137 to pigs, the levels of cesium-137 were measured in muscle tissue and the cumulative urinary and faecal excretion determined. Muscle tissue was examined in particular owing to its use in human nutrition. The difference in the levels of Cs-137 in individual muscles following both single and repeated doses were insignificant. The radioactivity in all the muscles decreased exponentially with time, the greatest decrease occurring in the first 14 days after administration. The levels of Cs-137 in individual muscles almost doubled when the single oral dose was doubled. The effective half-time of excretion of Cs-137 following repeated administration was between 17 to 20 days; however following the single dose, the effective half-time was 5 days. (UK)