Treatment of hypertension in patients with chronic renal failure has been shown to postpone the decline in renal function. Treatment with an ACE inhibitor has been shown to be superior to conventional antihypertensive treatment, but it is not known how an ACE inhibitor compares to treatment with a calcium channel blocker or to treatment with a combination of these drugs. The aim of the study was to evaluate the rate of decline in GFR in patients with chronic renal failure and hypertension treated with isradipine and spirapril as monotherapy and in combination.