Studies were conducted to determine the primary loci of gastrointestinal absorption of inorganic selenium in the chick using radiotracer techniques and Eimeria sp. infections of known site specificity for the gastrointestinal tract. Results showed that coccidial infections in the anterior regions of the small intestine reduced selenium absorption and potentiated selenium deficiency among chicks fed critical levels of the mineral. Absorption experiments showed that selenium absorption was greatest in the duodenum and anterior ileum, although selenium was bound at least transiently to tissues in the gizzard and crop. It is concluded from these experiments that dietary inorganic selenium is absorbed primarily in the duodenum and anterior ileum. Factors such as enteric disease which disrupt the integrity of the anterior intestinal mucosa can, therefore, reduce the absorption of selenium and other nutrients absorbed in that region, resulting in a potentiation of nutritional deficiencies.