The distribution of CRH in the brain and pituitary of the hagfish was examined.
CRH-ir cell bodies were seen in the preopticohypothalamic area and medulla oblongata.
Bundles of CRH-ir fibers were detected in the dorsal wall of the neurohypophysis.
CRH-ir fibers were distant from ACTH cells in the adenohypophysis.
It is suggested that CRH system exists in the hagfish.