The tissue activities of alkaline phosphatase (ALP),alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyltransferase (GGT), creatine kinase (CK), and lactate dehydrogenase (LDH) were determined in up to 13 selected tissues from seven scalloped hammerhead (Sphyma lewini), seven blue (Pnonace glauca), one sand bar shark (Carcharhinus plumbous), one sand tiger (Carchanas taurus), and two mako sharks (Isurus oxynnchus). Enzyme profiles in tissue homogenates were investigated using the same equipment and auto analytic methods used for diagnostic tests of serum samples. CK activity was greatest in muscle tissues, while LDH was most active in both the heart and white muscle. AST activity predominated in the heart, but was also found in many other tissues. The pattem for ALT varied by species, with the scalloped hammerhead, blue and mako sharks showing highest activity in liver, whereas the sand bar and sand tiger sharks had greater activity in stomach lining and kidney, respectively. ALP and GGT activities were concentrated primarily in the kidney of most specimens, though limited sampling of the testes in the blue shark revealed higher ALP activity in that tissue. Circulating serum enzyme levels were also determined for captive juvenile and adult sand tigers, and in free-ranging scalloped hammerhead and blue sharks, as reference values for diagnostic interpretation. Enzyme activity ranges (in IU/L) are shown below: