Objective: this study aimed to determine the association between HRV and hypertension young adult patients, the effect of antihypertensive medications on HRV parameters was also studied. Subjects and Methods: 70 subjects under age of 40 years were classified into two groups: A- Patients' group, It included 50 subjected they were classified according to type of antihypertensive medications into 3 subgroups; 1): 20 patients on ACE-I, (2): 15 patients on BB, 3): 15 patients on CCB. B)- Control group included 20 healthy subjects. Pulse rate, BP, ECG, and 24h Holter monitor were used to measure heart rate variability (HRV). Results: high statistical significant difference was found between patients and control according to SDNN rMSSD, pNN50 and LF/HF ratio ( P < 0.001). HRV parameters showed improvement in patient treated by BB and ACE-I, whereas no improvement was seen in patients treated by CCB. Conclusion: disturbed cardiac autonomic function was found in young hypertensive patients, treating such patients with either BB or ACE-I was associated with improvement of such autonomic imbalance.