Objective To investigate the antihypertensive effects of continuous airway positive pressure( CPAP) plus antihypertensive drugs on patients with obstructive sleep apnea hypopnea syndrome ( OSAHS) and hypertension.Methods 82 OSAHS patients with hypertension were enrolled in this study. They were randomly divided into a CPAP treatment group( 44 patients, treated with antihypertensive drugs and CPAP) , and a control group( 38 patients, treated with antihypertensive drugs only) . All the patients were performed polysomnography and 24-hour blood pressure monitoring before and 12 weeks after the treatment. Results After 12 weeks treatment, except the systolic pressure in night time( nSBP) , all the parameters of 24-hour blood monitoring improved better in the CPAP group than in the control group( all P lt; 0. 05) . The blood pressure dropped to normal in 75. 0% ( 33/44) CPAP patients and in 52. 6% ( 20 /38) control patients. In the CPAP group, 8( 18. 2% ) cases were withdrawn from antihypertensive drugs, 13( 29. 5% )cases required single agents, and 9( 20. 5% ) cases required three agents to achieve blood pressure control.But in the control group, all the patients needed two or more antihypertensive agents, in which 23( 60. 6% )patients needed three agents to achieve blood pressure control. After the treatment, the patients with dipping pattern blood pressure increased from10 to 29( 22. 7% -65. 9% , P lt;0. 05) in the CPAP group, and from10to 14( 26. 3% -36. 8%, P gt;0. 05) in the control group. Conclusions Combination therapy with CPAP and antihypertensive drugs controls blood pressure better than antihypertensive medication only for OSAHS patients with hypertension with fewer types of antihypertensive agents or even withdrawal from antihypertensive medication in some patients.