The phosphate (P_i) and calcium (Ca²⁺) homeostasis is mainly regulated by parathyroid hormone (PTH) and calcitriol. PTH after binding to its receptor (PTHR) induces the internalisation of the sodium dependent phosphate transporter type IIa in the kidney. NaPi IIa is at least in part responsible for renal P_i reabsorption also in goats. Under a high-P_i feeding regime, the PTHR expression should increase to reduce renal NaPi IIa. Therefore, more P_i could be excreted with urine to maintain the P_i homeostasis. The detection of the renal PTHR protein was carried out by Western analyses. Caprine NaPi IIa was verified on mRNA level by Northern analyses. The renal PTHR protein expression in brush border and basolateral membranes was significantly reduced under a high-P_i feeding regime. As a consequence of long-time high P_i feeding, the renal NaPi IIa was expressed on a low level. Therefore, the urinary P_i excretion was higher. The physiological meaning of PTHR mRNA and protein down regulation as well as of high plasma PTH levels in dP goats are still unclear. Assuming that renal NaPi IIa is the main target for PTH effect modulated by the PTHR, long-time adaptation to high-P_i could result in lower PTHR expression due to the lack of its target. If high P_i reduced the overall PTHR expression in the organism, high plasma PTH level could be adaptive to maintain PTH effects in non-renal organs.