A long term study designed to determine the biological effects of daily Sr{sup 90} ingestion in miniature swine has been underway in this laboratory since 1958. The Ultimate objective of this study is to provide data that will assist in defining for man the levels of dietary Sr{sup 90} at which there is no damage or negligible damage to him or his progeny. The animals being used in these studies are miniature swine which have a mature weight of 60 to 80 kg. The dietary requirements, gastrointestinal tract, and bone mass of miniature swine are quite similar to man. These factors, along with a relatively long life span, dictated their use in this study.