Background/Aims: Ventricular arrhythmia is associated with increased risk of cardiovascular events and death in the general population. Sudden death is a leading cause of death in end-stage renal disease. We aimed at evaluating the effects of ventricular arrhythmia on clinical outcomes in patients with earlier stages of chronic kidney disease (CKD). Methods: In a prospective study of 109 nondialyzed CKD patients (estimated glomerular filtration rate 34.8 ± 16.1 ml/min/1.73 m2, 57 ± 11.4 years, 61% male, 24% diabetics), we tested the hypothesis that the presence of subclinical complex ventricular arrhythmia, assessed by 24-hour electrocardiogram, is associated with increased risks of cardiovascular events, hospitalization, and death and with their composite outcome during 24 months of follow-up. Complex ventricular arrhythmia was defined as the presence of multifocal ventricular extrasystoles, paired ventricular extrasystoles, nonsustained ventricular tachycardia, or R wave over T wave. Results: We identified complex ventricular arrhythmia in 14% of participants at baseline. During follow-up, 11 cardiovascular events, 15 hospitalizations, and 4 deaths occurred. The presence of complex ventricular arrhythmia was associated with cardiovascular events (p < 0.001), hospitalization (p = 0.018), mortality (p < 0.001), and the composite outcome (p < 0.001). In multivariate Cox regression analysis, adjusting for demographic characteristics, complex ventricular arrhythmia was associated with increased risk of the composite outcome (HR 4.40; 95% CI 1.60-12.12; p = 0.004). Conclusion: In this pilot study, the presence of asymptomatic complex ventricular arrhythmia was associated with poor clinical outcomes in nondialyzed CKD patients.