1. The effects of stimulation of the peripheral ends of both vagus nerves below the heart (10 Hz for 10 min) were investigated in conscious calves 2-5 weeks after birth. 2. Stimulation was invariably below behavioural threshold and caused a prompt increase in the concentrations of pancreatic glucagon, insulin and pancreatic polypeptide (PP) in the arterial plasma. Each of these responses was blocked by pretreatment with atropine (0.2 mg/kg). 3. Administration of exogenous glucose by continuous I.V. infusion (ca. 0.08 mmol kg-1 min-1) greatly enhanced the release of insulin in response to vagal stimulation without significantly changing that of pancreatic glucagon or PP. 4. Vagal stimulation also caused a significant rise in the concentration of vasoactive intestinal peptide (VIP) in the intestinal lymph and this response was found to persist in the presence of atropine.