Background Left ventricular mass (LVM) is a widely used surrogate end point in randomized trials involving people with chronic kidney disease (CKD) because treatment-induced LVM reductions are assumed to lower cardiovascular risk. The aim of this study was to assess the validity of LVM as a surrogate end point for all-cause and cardiovascular mortality in CKD. Study Design Systematic review and meta-analysis. Setting & Population Participants with any stages of CKD. Selection Criteria for Studies Randomized controlled trials with 3 or more months’ follow-up that reported LVM data. Intervention Any pharmacologic or nonpharmacologic intervention. Outcomes The surrogate outcome of interest was LVM change from baseline to last measurement, and clinical outcomes of interest were all-cause and cardiovascular mortality. Standardized mean differences (SMDs) of LVM change and relative risk for mortality were estimated using pairwise random-effects meta-analysis. Correlations between surrogate and clinical outcomes were summarized across all interventions combined using bivariate random-effects Bayesian models, and 95% credible intervals were computed. Results 73 trials (6,732 participants) covering 25 intervention classes were included in the meta-analysis. Overall, risk of bias was uncertain or high. Only 3 interventions reduced LVM: erythropoiesis-stimulating agents (9 trials; SMD, −0.13; 95% CI, −0.23 to −0.03), renin-angiotensin-aldosterone system inhibitors (13 trials; SMD, −0.28; 95% CI, −0.45 to −0.12), and isosorbide mononitrate (2 trials; SMD, −0.43; 95% CI, −0.72 to −0.14). All interventions had uncertain effects on all-cause and cardiovascular mortality. There were weak and imprecise associations between the effects of interventions on LVM change and all-cause (32 trials; 5,044 participants; correlation coefficient, 0.28; 95% credible interval, −0.13 to 0.59) and cardiovascular mortality (13 trials; 2,327 participants; correlation coefficient, 0.30; 95% credible interval, −0.54 to 0.76). Limitations Limited long-term data, suboptimal quality of included studies. Conclusions There was no clear and consistent association between intervention-induced LVM change and mortality. Evidence for LVM as a valid surrogate end point in CKD is currently lacking.