Data are tabulated on the distribution of strontium-90 in lactating and pregnant goats, milk, and fetuses following the administration of single and multiple oral doses of strontium-90. Excretion and retention data are discussed. Strontium-90 was readily taken up in many tissues of the fetus, especially those containing calcium. Strontium-90 was found to accumulate in the udder before milk excretion started and thus affected the activity of first milk. (C.H.)