Background: Cardiac autonomic dysfunction is strongly associated with an increased risk of cardiac arrhythmias and sudden cardiac death in post-myocardial infarction, hypertension, heart failure, diabetes, etc. The measurement of heart rate variability (HRV) based on 24-hour ECG Holter recording has become an important method of assessment of cardiac autonomic dysfunction. The changes of HRV indexes are significant and predictors of ventricular arrhythmias. Objective: To investigate HRV and cardiac arrhythmias using 24-hour Holter monitoring in hypertension patients, the changes of HRV indexes versus severe ventricular arrhythmias in systemic hypertension. Method: To investigate HRV and cardiac arrhythmias using 24-hour Holter monitoring in 81 systemic hypertension patients compared to 30 normotensive. The subjects in two groups were matched for age, gender and body mass index (BMI). Results: Our results showed that inthe hypertensive group, there were significantly lower parasympathetic HRV indexes (SDANN5, SDNN, ASDNN5, RMSSD) and higher ventricular arrhythmias. Reduced SDANN5, SDNN were associated significantly with an increased risk of severe ventricular arrhythmias (SDANN5 or