There is a unique relationship between the kidney and blood pressure. The importance of the kidney on the pathogenesis of hypertension was clearly demonstrated in renal transplantation studies both in genetic hypertensive rats and humans with hypertension. Also, hypertension accelerates loss of function of the diseased kidney and the antihypertensive treatment attenuates the progression of various renal diseases. A lot of mechanisms to explain this relationship are considered: salt retention, abnormalities of renal hemodynamics, inappropriate activation of the renin-angiotensin system etc. This review is an attempt to highlight a renal role on the development of hypertension, especially in diabetic nephropathy.