Spontaneously hypertensive rats (SHR) that underwent uninephrectomy (UNX) at six weeks of age were randomly assigned to receive no treatment, the calcium channel blocker, nifedipine, or the angiotensin converting enzyme inhibitor, enalapril. Both drugs reduced systemic blood pressure, however, blood pressure tended to be greater in rats given nifedipine than in those on enalapril. After six months, proteinuria and the relevance of glomerula sclerosis were significantly reduced in the two treated groups compared to values observed in untreated SHR. Kidney weight was also reduced by therapy, suggesting that both enalapril and nifedipine inhibited compensatory kidney growth. Micropuncture studies performed in similarly treated groups of rats, but at 11 weeks of age, revealed that PGC was elevated in untreated UNX SHR and reduced by both nifedipine and enalapril. These findings support the hypothesis that glomerular hypertension and renal hypertrophy are important risk factors for glomerular injury. They suggest that calcium blockers are as effective as angiotensin converting enzyme inhibitors in preventing progressive kidney damage.