Three anionic and one or more cationic isozymes exhibiting glutamic-oxal-acetic transaminase activity have been separated by starch gel electrophoresis of rat liver, heart and muscle extracts. The fastest migrating, third, anodic band does not appear to be present in rat kidney. Four anodic bands were found in a purified enzyme preparation from pig heart. There are species differences in rate of migration of the isozymes which suggest structural differences in the enzyme proteins from the various sources. A direct, one-step, stain procedure, using a diazonium salt which couples specifically with oxalacetate, is described for detection of the transaminase on starch gel.