Administration of bovine parathyroid hormone (PTH) preparations increased the phosphate concentration in the parotid saliva of sheep. Data on the site of action of PTH (1-84) were obtained by (a) equimolar infusions of PTH (1-84) and (1-34) directly into the arterial blood supply of the vascularly isolated parotid gland in anaesthetized sheep, (b) intravenous infusion of PTH (1-84) at a similar rate and (c) intra-arterial infusion of PTH (1-84) with complete drainage of the venous effluent from the gland during the infusion. Results showed substantial time- and dose-response identity of the two peptides, at 10(-9) to 4 X 10(-9) mol/l in arterial blood, in raising salivary phosphate concentration. The effect of PTH (1-84) was not due to recirculated fragments because the response was obtained when recirculation was prevented by complete venous drainage and little or no response occurred when the same infusion was given i.v.