This study sought to investigate the cardiac and renal effects of rigorous versus standard BP control on autosomal-dominant polycystic kidney disease (ADPKD). A prospective, randomized, 7-yr study was performed to examine the effect of rigorous (<120/80 mmHg) versus standard (135-140/85-90 mmHg) BP control on left ventricular mass index (LVMI) and kidney function in 75 hypertensive ADPKD patients with left ventricular hypertrophy. LVMI was measured by echocardiogram at baseline and at 1 and 7 yr. Renal function was assessed by measuring serum creatinine and 24-h creatinine clearance every 6 mo for 3 yr, then annually for an additional 4 yr. The baseline characteristics were comparable in the two groups. During the study, average mean arterial pressure was 90 +/- 5 mmHg for the rigorous group and 101 +/- 4 mmHg for the standard group (P < 0.0001). The LVMI decreased by 21% in the standard group and by 35% in the rigorous group. A mixed model longitudinal data analysis revealed that rigorous BP control was significantly more effective in decreasing LVMI (P < 0.01). There was no statistically significant difference in renal function between the two groups. In conclusion, left ventricular hypertrophy, a major cardiovascular risk factor, was decreased to a significantly greater extent by rigorous than standard BP control. This finding has particular clinical importance because cardiovascular complications are the most common cause of death in ADPKD patients.