AbstractThe spiny lobster stomatogastric ganglion has been shown to be innervated by catecholaminergic processes which derive from cells of large central ganglia (Kushner and Maynard, 1977). Biochemical evidence had indicated that the stomatogastric system synthesizes dopamine and not norepinephrine from tritiated tyrosine (Barker, Kushner, and Hooper, 1979). Studies reported here document that the stomatogastric ganglion itself contains dopamine, as measured with a sensitive endogenous assay. Moreover, the ganglion can synthesize dopamine from tritiated tyrosine or DOPA. Additionally, when incubated in tritiated dopamine, the ganglion takes up dopamine and protects it from degradation; this process is inhibited by cocaine. When incubated with3H‐tyrosine, small but measurable amounts of tritiated dopamine were detected in the medium surrounding the ganglio