Anorexia is a major manifestation of zinc deficiency, but the mechanism (s) for this anorexia are not well defined. In this study we investigated the effects of three modulators of feeding response on the food consumption of zinc deficient rats. Zinc deficient rats showed partial resistance to norepinephrine, eating significantly less at the 20 μg dose than the zinc sufficient ad lib controls, and food ingestion could not be induced at the 10 μg dose. Similarly, higher doses of the GABA agonist, muscimol, were required to induce feeding in the zinc deficient animals compared to the zinc sufficient controls. The dopamine agonist, bromergocryptine, failed to induce feeding in the zinc deficient animals. These findings are compatible with the concept that zinc deficiency produces a generalized decrease in receptor responsitivity, possibly secondary to alterations in membrane fluidity.