This chapter discusses animal-derived flesh foods, for example meat. It considers the state–of–the–art of isotope analyses of flesh foods. Isotopic variations of the elements found in flesh foods record a range of information about source, derivation, or history. In contrast to the elements H, C, N, O, and S, strontium is not recognized as an element essential for life. It is found in trace amounts, compared to the bio–elements, and has been used less frequently in isotopic investigations of flesh foods since analysis requires clean laboratory facilities. Strontium isotope variation is linked principally to variation in an animal's local geology. The chapter focuses on aquatic flesh foods, derived from animals living most or all of life in freshwater or saltwater environments. It reviews the use of hydrogen, carbon, nitrogen, oxygen, sulfur, and strontium isotopes to investigate the authenticity and origin of flesh foods, or meat, both terrestrial and aquatic.