A condition involving the growth of the myocardium that exceeds hemodynamic needs has been reported and called as inappropriate left ventricular mass (LVM). The appropriateness of LVM can be estimated by the ratio of observed LVM to predicted LVM. The excessive growth of LVM is frequently noted in patients with chronic kidney disease (CKD). This study is designed to assess whether the ratio of observed to predicted LVM is a useful prognostic indicator of cardiovascular events in patients with moderate to advanced CKD. We consecutively enrolled 485 patients with CKD stages 3-5 from our Outpatient Department of Internal Medicine. Inappropriate LVM was defined as observed LVM more than 28% greater than the predicted value. The relative risk of cardiovascular events was analyzed by Cox-regression methods. There was a significant trend for a stepwise increase in the observed/predicted LVM ratio (P<0.001) and the prevalence of inappropriate LVM (P=0.003) corresponding to advances in CKD stages. In the multivariate analysis, old age, a history of coronary artery disease, congestive heart failure, atrial fibrillation, wide pulse pressure, decreased serum albumin and hemoglobin levels, left atrial diameter >4.7 cm and increased observed/predicted LVM were independently associated with increased cardiovascular events. Our findings show that increased observed/predicted LVM is independently associated with adverse cardiovascular outcomes in patients with CKD stages 3-5.