Hypertension possess a significant risk factor for a variety of diseases and affects millions of people all around the world. Recent studies suggest that NO plays a role in pathogenesis of hypertension while some investigators find a close relationship between acupuncture treatment and NO levels. We therefore aimed to investigate the effect of acupuncture on the levels of blood pressure and nitric oxide (NO) in hypertensive patients. After obtaining institutional ethics committee approval and patients' informed consent, 32 essential hypertensive patients aged between 32-65 and taking antihypertensive drugs were included to the study. A total of 10 sessions of manual acupuncture were applied on body acupoints (EX-HN3 (Yintang), KI 3, LIV 3, SP 9, LI 4, HT 7, ST 36, SP 6) in 10 weeks. Systolic (SBP) and diastolic blood pressure (DBP) levels and blood NO levels were measured for 3 times (i.e. before & after the first session, and after the 10th session). Main outcome measures of our study were the changes in SBP and DBP as well as nitric oxide levels between 3 measurements were compared. Our study showed that SBP and DBP values decreased both after the 1st and 10th sessions of acupuncture treatments (p<0.05). The NO concentration also increased both after the 1st (71.5%) and 10th sessions (184.6%) (p<0.05).