Parathyroid hormone (PTH) acts on a large number of cells derived from many different tissues that are not traditional targets (kidney and bone) for their action. Also, the acute exposure of many of these cells to PTH resulted in the generation of cAMP. These observations are consistent with the presence of PTH receptors on these cells. However, there is no evidence that the cells that are not traditional targets for PTH, express the receptor of the hormone. The cloning of the PTH-PTH related protein (PTH-PTHrP) receptor provided the tool to examine whether these cells contain the mRNA for this receptor. Poly A+RNA from a variety of rat tissues was probed with a 1,200-bp fragment of the cDNA of the PTH-PTHrP receptor by the Northern blot technique. We found that mRNA for the PTH-PTHrP receptor is present in the heart, brain, spleen, lung, liver, skeletal muscle, kidney and testis. Transcripts of 2.4 kb were found in all these tissues with the strongest expression in the kidney. In addition, smaller RNAs were detected in the kidney (approximately 1.8 kb) and testis (1.5 kb). These results indicate that many cell types express the PTH-PTHrP receptor gene. The data provide a possible explanation for the direct effects of PTH on so many cells and for the understanding of the harmful effects of chronic excess of PTH on the function of many organs in chronic renal failure.