Left ventricular (LV) hypertrophy is an established cardiovascular risk factor, yet little is known about its trajectory in people with chronic kidney disease. The goal of this prospective research study was to describe the trajectory of LV mass index, its relationship with blood pressure (BP), and specifically to compare the relationship of BP measured in the clinic and 24-hour ambulatory BP monitoring with LV mass index. Among 274 veterans with chronic kidney disease followed for over ≤ 4 years, the rate of growth of log LV mass index was inversely related to baseline LV mass index; it was rapid in the first 2 years, and plateaued subsequently. Systolic BP also significantly increased, but linearly, 1.7 mm Hg/y by clinic measurements and 1.8 mm Hg/y by 24-hour ambulatory BP. Cross-sectional and longitudinal associations of both clinic BP and 24-hour ambulatory BP with LV mass index were similar; both BP recording methods were associated with LV mass index and its growth over time. Controlled hypertension, masked uncontrolled hypertension, and uncontrolled hypertension categories had increasing LV mass index when diagnosed by 24-hour ambulatory and awake BP (P<0.05 for linear trend) but not sleep BP. After accounting for clinic BP both at baseline and longitudinally, LV mass index among individuals was additionally predicted by the difference in sleep systolic BP and clinic systolic BP (P=0.032). In conclusion, among people with chronic kidney disease, the growth of LV mass index is rapid. Research-grade clinic BP is useful to assess LV mass index and its growth over time.