In an earlier study we found more than twice as many vasopressin (AVP) neurons in the suprachiasmatic nucleus (SCN) of homosexual men as compared to heterosexual men. The present measurements in the same individuals showed that there is no difference in the number of vasoactive intestinal polypeptide (VIP)-expressing neurons in the SCN. The reduced nuclear diameter of both VIP and AVP neurons in the SCN as found in homosexual men points to metabolic alterations in the SCN in relation to sexual orientation.