This study describes for the first time the ability of catecholamines to induce limb autotomy in the Dungeness crab, Cancer magister. Different concentrations of the biogenic amines dopamine (DA), serotonin, octopamine, norepinephrine, epinephrine, and tyramine, as well as L-dopa and catechol, were individually tested for their ability to elicit autotomy in C. magister. Only the catecholamines dopamine, norepinephrine, and epinephrine were able to stimulate autotomy, whereas the monoamines serotonin, octopamine, and tyramine were not. L-dopa and catechol were also not capable of stimulating autotomy. This suggests that the two phenyl hydroxyl groups on the catechol ring are necessary for ligand/DA receptor binding, whereas the particular biochemical properties of the ethylamine functional group confer ligand/DA receptor binding specificity. Dopamine-stimulated autotomy was concentration-dependent. The D1 receptor agonists and D1 and D2 receptor antagonists failed to respectively induce and inhibit autotomy, which may indicate the presence of a novel subtype of DA receptor in C. magister. Although the particular site of DA injection did not significantly affect the number of legs autotomized, it did appear to influence which legs autotomized. This suggests that DA acts locally, either as a neuromodulator or a neurotransmitter at local nerve synapses or neuromuscular junctions, rather than centrally through neurons descending from the central nervous system.