1. Left or right cervical vagotomy caused elevated intakes of water after hypertonic saline, isoprenaline and polyethylene glycol compared with normal rats. In cervically vagotomized rats sodium nitrite caused a dose-dependent water intake whereas in normal rats it produced a smaller, more variable response. The same procedure also reduced the extent to which drinking following overnight water deprivation was inhibited by plasma volume expansion. Drinking after diazoxide or in response to ligation of the abdominal inferior vena cava was not affected by cervical vagotomy. 2. The antidiuresis that followed isoprenaline treatment was greater in cervically vagotomized than normal rats; that which occurred after caval ligation was unaffected. 3. Subdiaphragmatic vagotomy did not alter water intake in response to hypertonic saline, isoprenaline or polyethylene glycol. 4. It is concluded that nerves within the supradiaphragmatic distribution of the vagi modify water intake in response to changes in the degree of vascular filling.