Background Hypertension is the major health burden associated with increased cardiovascular morbidity and mortality. Positive family history and stress are the risk factors for hypertension. The present study aims to evaluate the effect of acute stress on the cardiac autonomic modulation in normotensive individuals with parental history of hypertension. Methods Sixty healthy male volunteers (30 with parental history of hypertension-NTPH+ group and 30 without parental history of hypertension-NTPH- group) in the age group of 18-24 years were included in the study. Short-term baseline heart rate variability (HRV) evaluation was done in frequency domain. Volunteers performed mental arithmetic stress task (MAST). HRV was measured before MAST, during MAST, and recovery period. HRV in both groups were compared. Results Analysis showed a significant increase in heart rate (p-value = 0.038) and systolic blood pressure (p-value = 0.01) in NTPH+ group compared to the NTPH- during MAST. NTPH+ group showed significantly higher LFnu (p-value = 0.03) and LF/HF ratio (p-value = 0.02) during MAST. Reduction in HFnu (p-value = 0.027) was significantly higher in the study group. ANOVA analysis demonstrated significant increase in LFnu [F(2.602, 75.46) = 18.60; p < 0.001; etap2 = 0.391] and LF/HF ratio [F(1.76, 51.043) = 29.952; p < 0.001; etap2 = 0.508] during MAST and 10 min of recovery period from baseline value in NTPH+ group. HFnu has significantly reduced during MAST and 5 min recovery period from baseline value in NTPH+ group [F(2.78, 80.72) = 12.77; p = 0.033, etap2 = 0.28]. Conclusions Acute mental stress leads to exaggerated sympathetic response and vagal suppression in healthy individuals with parental history of HTN. This study concludes that HRV, which reflects autonomic flexibility, is lower during acute mental stress and post-stress recovery period in normotensive males with parental history of HTN.