Amenorrhea is one of the cardinal features of anorexia nervosa and is associated with hypothalamic dysfunction. Earlier theories of weight loss, decreased body fat, or exercise do not fully explain the etiology of amenorrhea in anorexia nervosa. Disturbances in central dopaminergic and opioid activity have been described in anorexia nervosa and both these substances are known to modulate gonadotropin-releasing hormone (GnRH)-mediated luteinizing hormone (LH) release. Serum LH, folliclestimulating hormone (FSH), estradiol, and prolactin levels were measured at baseline and after administration of metoclopramide (a central D-2 dopamine receptor blocker) in 10 newly diagnosed women with anorexia nervosa and in 10 healthy age-matched controls. Basal prolactin levels and the prolactin response to metoclopramide were significantly impaired in the group with anorexia nervosa. Metoclopramide did not induce a significant rise in LH levels in either the anorexic or the control groups. Neurotransmitter abnormalities may influence hypothalamic dysfunction in anorexia nervosa but the exact mechanism remains to be determined. © 1994 by John Wiley & Sons, Inc.