The presence of selenium (Se) in foods and the pertinent toxicological data are reviewed. In most regions of the world, the average daily intake of man is thought to be between 60 and 250 micrograms for adults and between 4 and 35 micrograms for infants. The current practice of adding selenium supplements to animal feeds may increase the selenium content of meats by up to 30%, but this does not result in a biologically meaningful increase in the selenium intake of people. Se is mostly absorbed after ingestion, according to the available metabolic data. Up to 50% of it is eliminated in the urine, while the remaining percentage builds up primarily in the liver and kidneys. Recent epidemiological and animal studies show that Se is not a carcinogen, and in some cases may have anti-cancer properties. Neither the essentiality for man, nor the no-effect level of Se have been established.