Autosomal dominant polycystic kidney disease (ADPKD) is a common hereditary condition that may be diagnosed in utero. Our goal was to evaluate symptoms of ADPKD in children, including left ventricular mass index (LVMI), renal volume, renal function and microalbuminuria in relation to systolic and diastolic blood pressure. Eighty-five children were stratified by blood pressure into three cohorts: hypertensive (95th percentile and over), borderline hypertensive (75-95th percentile) and normotensive (75th percentile and below). There were no differences in gender, age, height, renal function, or microalbuminuria between the groups. Both the hypertensive and borderline hypertensive children had a significantly higher LVMI than normotensive children, with no significant difference between hypertensive and borderline hypertensive groups. There was a significant correlation between renal volume and both systolic and diastolic blood pressures in all subjects. Renal volume in hypertensive children was significantly larger than in the borderline hypertensive group, with no significant difference between normotensive and borderline hypertensive groups. These findings show that an increase in LVMI may be detected earlier than an increase in renal volume in children with ADPKD and borderline hypertension, suggesting that close monitoring of cardiac status is indicated in these children.