Renal Sympathetic Nerves and Ventricular Arrhythmias Introduction Renal sympathetic nerve (RSN) activity plays a key role in systemic sympathetic hyperactivity. Previous studies have shown that cardiac sympathetic hyperactivity, especially the left stellate ganglion (LSG), contributes to the pathogenesis of ventricular arrhythmias (VAs) after acute myocardial infarction (AMI). Methods and Results Twenty‐eight dogs received 3 hours of continuous left‐sided electrical stimulation of RSN (LRS; Group‐1, n = 9), sham RSN stimulation (Group‐2, n = 9), or LSG ablation plus 3 hours of LRS (Group‐3, n = 10) were included. AMI was induced by ligating the proximal left anterior descending coronary artery. LRS was performed using electrical stimulation on the adventitia of left renal artery at the voltage increasing the systolic blood pressure (BP) by 10%. BP, heart rate variability (HRV), serum norepinephrine (NE) level, and LSG function were measured at baseline and the end of each hour of LRS. C‐fos and nerve growth factor (NGF) protein expressed in the LSG were examined in Group‐1 and Group‐2. Compared with baseline, 3 hours of LRS induced a significant increase in BP, sympathetic indices of HRV, serum NE level, and LSG function. The incidence of VAs in Group‐1 was significantly higher than other groups. The expression of c‐fos and NGF protein in the LSG was significantly higher in Group‐1 than Group‐2. Conclusion Three hours of LRS induces both systemic and cardiac sympathetic hyperactivity and increases the incidence of ischemia‐induced VAs.