Abstract： Objective To analyze the effects of long term nasal continuous positive airway pressure on the blood pressure of patients with OSAHS.Methods From April 1997 to October 2008,2898 patients from the First Affiliated Hospital of Fujian Medical University who complained snore during sleeping were studied.Nine hundred eighty cases were diagnosed as OSAHS with hypertension,and these patients were randomly divided into 2 groups:one group was treated with antihypertensive drugs and nasal continuous positive airway pressure (nCPAP), while the other group only received antihypertensive drugs.The polysomnography(PSG) was recorded during sleeping and the blood pressure was remeasured after 6 months or more. All patients were followed up for 5 years to observe the long-term effects of nCPAP or drugs.Results Systolic and diastolic blood pressure in the nCPAP group significantly decreased after 6 months [(125±16)mmHg (1 mm Hg=0.133 kPa) vs (136±19)mm Hg,(83 ±10)mm Hg vs (95 ±15)mmHg,P ＜ 0.05 ],and the decreasing extent of blood pressure in nCPAP group was more notable than antihypertensive drug group [ decreasing extent of systolic blood pressure:( 10 ± 11 )mm Hg vs (4 ± 11 )mmHg ; decreasing extent of diastolic blood pressure:( 11 ± 7 )mm Hg vs ( 6 ± 7 )mm Hg; P ＜ 0.05 ].The total effective rate in nCPAP group was significantly higher than that in antihypertensive drug group (90％ vs 38％,P ＜0.01).One hundred and eighty three cases in nCPAP group and 157 cases in antihypertensive drug group completed the 5-year follow-up and the blood pressure was controlled within the normal range.Some patients could gradually reduce or stop the use of antihypertensive drugs and the blood pressure didn' t appear to rebound. The number of antihypertensive drugs in the nCPAP group was significantly fewer as compared to the antihypertensive drugs group after 2,3,4 and 5 years' follow-up.Conclusions nCPAP is a safe and effective treatment for high blood pressure in patients witb OSAHS.