BACKGROUND: We assessed the effect of blood pressure (BP) control on left ventricular mass index (LVMI) and left ventricular hypertrophy (LVH). METHODS: Ninety-six patients (64 males) ≥9 months post–kidney transplantation from the 4C-T (Cardiovascular Comorbidity in Children with Chronic Kidney Disease and Transplantation) study were analyzed longitudinally (mean follow-up, 2.6±1.3 years). Cumulative systolic blood pressure (SBP)/diastolic BP exposure was calculated as a time-averaged area under the curve and categorized: ≤50th, 50th to ≤75th, 75th to ≤90th, and >90th percentile (pct). We performed adjusted linear and logistic mixed models for LVMI and LVH, respectively. RESULTS: At baseline, LVMI was 49.7±12.7g/m ^2.16 with 64% (n=61) kidney transplantation recipients displaying LVH. Compared with patients with cumulative SBP exposure >90th pct, patients with cumulative SBP of 50th to ≤75th showed a significant LVMI reduction of −5.24g/m ^2.16 ( P =0.007). A similar tendency was seen for cumulative SBP≤50th (β=−3.70 g/m ^2.16 ; P =0.067), but patients with cumulative SBP of 75th to ≤90th pct showed no reduction. A post hoc analysis in patients with cumulative SBP≤75th revealed that median SBP exposure was at 57.5th pct. For cumulative diastolic BP, a significant LVMI reduction was seen in all 3 categories ≤90th pct compared with patients >90th pct. Patients with cumulative SBP of ≤50th or 50th to ≤75th pct showed 79% or 83% lower odds of developing LVH, respectively. Patients with cumulative diastolic BP ≤50th showed a tendency of 82% lower odds for LVH (95% CI, 0.03–1.07). CONCLUSIONS: Stricter BP control led to regression of LVMI and LVH. Our data suggest a BP target below the 60th pct, which needs to be substantiated in a randomized controlled trial.