The autonomic innervation of the ovary of the Atlantic cod was investigated using histochemical and physiological/pharmacological methods. The paired ovary receives autonomic innervation via branches of the posterior splanchnic nerve (vesicular nerve).Histochemical studies demonstrated vasoactive intestinal polypeptide (VIP)-immunoreactive, 5-hydroxytryptamine-immunoreactive and adrenergic nerve fibers, but a number of antisera raised against other peptides failed to reveal any specific reaction in the tissue preparations. It is concluded that the cod ovary receives a double antagonistic autonomic innervation of excitatory cholinergic fibers and non-adrenergic inhibitory fibers. The nature of the inhibitory neurotransmitter is not known.