Taurine is a beta amino sulfonic acid found ubiquitously in animal tissues but found only rarely in plants. Most mammals synthesize taurine from the sulphur amino acids, methionine and cysteine so this important metabolite is generally not an essential nutrient. Taurine has been shown to be an essential nutrient for the feline and some evidence exists that indicate that it may be a dietary requirement for many carnivores. A taurine deficiency in cats includes deficits in eyesight, hearing, heart function, reproduction and the immune system. The metabolic dysfunctions that results in these disorders are not understood and have been elusive for many investigators. The most fully understood functions of taurine are its roles in bile acid conjugation and in osmoregulation. The importance of the metabolic functions is not known for cetaceans or whether they can synthesize taurine or whether it is a dietary essential for these animals. Since it is known that taurine is the most abundant amino acid in cetacean milk it was decided to determine the concentration of taurine in plasma and whole blood of cetaceans. The concentration of taurine in plasma of killer whales (n=9), Tursiops truncates (n= 16) and Kogia breviceps (n= 1) ranged from 82-121, 42-100 and 16-20 nmols/mL, respectively while the whole blood taurine concentrations ranged from 173-420, 161-218 and 89nmols/mL respectively. These concentrations are similar to that found in the feline and canine species whereas the whole blood concentrations are considerably lower. Since there are no known clinical signs associated with low plasma taurine in these species, more work needs to be done to ascertain whether the low whole blood taurine concentrations indicate that taurine is less important in some of the blood cells and/or whether less taurine is necessary for metabolic functions generally in these species.