The present anatomical investigation showed that, in 10 cavernous sinuses of human beings studied, we found neurons with morphological characteristics similar to those found in the autonomic nervous system ganglia. Sometimes these neurons were found isolated alongside nerve fibres; otherwise grouped in ganglia. These cells were more frequent in the middle part of the sinus and in the vicinity of the internal carotid artery and abducent nerve. We also observed a bundle of fibres connected with neurons and bundles of fibres being incorporated to (or leaving?) the abducent nerve.