1. Two groups of adult rats were placed in a metal-free environment and pair-fed with selenium-supplemented and Se-deficient diets.
2. After 5 months the animals were killed and skeletal muscle concentrations of creatine, creatine phosphate, ATP, protein and Se were determined.
3. Se deficiency was indicated by the low Se content of the skeletal muscle from the deficient animals, but no changes were found in the amounts of the other components.
4. These results suggest that Se may not be involved in creatine metabolism and that Se deficiency may not be concerned independently in the development of nutritional dystrophy, where changes are found in the levels of protein, creatine, creatine phosphate and ATP.