Intracerebroventricular (icv) injection of glucagon-like peptide-1 (7-36) amide (GLP-1) has been shown to reduce food intake in rats. In these studies, we confirmed that injection of 10 μg of GLP-1 into the third cerebroventricle suppressed food intake. Moreover, we observed a reduction in water intake associated with the decreased food intake. We further examined whether GLP-1 injected icv in rats has a specific inhibitory effect on water intake. It was found that GLP-1 reduced water deprivation-induced drinking. Furthermore, the same dose of GLP-1 (10 μg) was sufficient to condition taste aversion. Finally, when 2 μg of GLP-1 were injected into the third ventricle, it only suppressed water deprivation-induced water intake and failed to influence spontaneous food and water intakes or induce conditioned taste aversion. These observations indicate that GLP-1 is a potent inhibitor of water intake in the rat and may play a role in the control of fluid homeostasis.