The phospholipase C (PLC)-mediated intracellular signal transduction pathway is considered to be involved in the regulation of blood pressure. However, little information is available concerning the distributional and functional significance of PLC in the genetic hypertensive rats. As the first step of knowing the role of PLC on hypertension, we investigated the distribution of 6 PLC isozymes (PLC-β1, -β3, -β4, -γ1, -γ2 and -δ1) in the heart and brain, which are concerned with hypertension, in the normotensive Wistar-Kyoto rat (WKY) and spontaneously hypertensive rat (SHR) using the western blotting and immunocytochemistry. The immunoreactivities of PLC isozymes in brain were detected, but there were no distributional and quantitative differences between the WKY and SHR. In the heart, but the immunoreactivities to PLC-β1 and -γ2 in the SHR were higher than those in WKY. In immunocytochemistry to confirm these western blotting data, PLC-β1 and -γ2 were localized in cardiac myocytes and the intensities of immunoreactivity in SHR were stronger than that in WKY. These results suggest that PLC-β1 and -γ2 would have possibility to concern with the establishment of spontaneous hypertension.