Background: Blood pressure (BP) levels variety throughout the day, both by internal stimuli and the influence of external factors. The BP which measured at the clinic are higher than self measurement at home. Deep breathing (DB) is a technique which deep breaths <10x/minute,which can lower BP through activation of chemoreceptors and baroreceptors. The aim of this study is to know the effect of DB on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the normo-prehypertensive population. Methodology: This study design was one-group pre-post test clinical trials. automatic blood pressure monitoring (Omron HEM-7320) was measured in 119 subjects, aged 25-50 years. Measurements without DB after the subject sat down for 5 minutes of rest followed by the 1st, 3rd and 5th minute measurements when the subject was resting, BP measurement DB after the subject sits rest 5 minutes then performed (breathing 8 cycle/min following the rhythm by the application paced simulation breath on smarthphone android) continued measurement at 1 minute, 3rd and 5th after DB. Results: 56 male and 63 female, where 66 subjects found normotensive and 53 subjects prehypertensive. The largest decrease in SBP after Deep Breath Test (DBT) at 1st minute (6.61+3.9 mmHg) followed by 3rd and 5th (5.56+4.7 and 3.38+5.3 mmHg), while DBP at 1st minute (3,33+4,34 mmHg) followed by 3rd and 5th (2,34+4,14 and 1,11+4,71 mmHg). The comparison between the reduction of SBP and DBP before DB and after DB was statistically significant at 1st and 3rd minute (0.9+3.1vs 6.6+3.9mmHg), (1.5+3.6vs5.6+4.8mmHg) and DBP in 1st and 3rd minute (0.8+4.3vs3.3+4.3mmHg), (1.3+4.9vs2.3 +4.1mmHg) (P<0.05). At 5th minutes, the change was statistically significant only in SBP (1.4+4.1vs3.4+5.4mmHg)(p=0.002),while the DBP was not statistically significant (1.4+5.0vs1.1+4.7mmHg) (p=0.699) Conclusion: Deep Breathing descreased SBP and DBP significantly,especially in the first minute followed with third and fifth minutes.