Renal transplantations were performed using stroke-prone spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) as kidney donors and bilaterally nephrectomized F1 hybrids, bred from SHR x WKY parents as renal graft recipients. Recipients of renal grafts from adult, naive SHR but not from adult normotensive WKY kidney donors developed post-transplantation hypertension. Permanent blood pressure normalization by antihypertensive treatment in adult SHR kidney donors, as well as the young, prehypertensive age of SHR kidney donors reduced but did not prevent the development of post-transplantation hypertension. Increasing renal perfusion pressure in WKY kidney donors (chronic 2-kidney 1-clip renovascular hypertension) also resulted in post-transplantation hypertension in recipients of the non-clipped kidneys. Blood pressure remained normal in recipients of renal grafts from young WKY kidney donors. These data suggest that SHR kidneys carry a genetic defect which can give rise to post-transplantation hypertension and which therefore may also play a role in the development of hypertension in naive SHR. In addition, secondary hypertension-induced renal damage may also contribute to post-transplantation hypertension in recipients of renal grafts from hypertensive donors.