Objective : To investigate the correlation between obstructive sleep apnea hypopnea syndrome (OSAHS ) and hypertension and its risk factors ,so as to provide basis for prevention and treatment of OSAHS accompanied by hypertension . Methods : A total of 108 OSAHS patients were enrolled and the general conditions were recorded . The blood pressure at 22 ∶ 00 before sleep and that at 8 ∶ 00 . next morning was determined routinely ,and the blood lipid level was detected . According to apnea hypoapnea index (AHI) ,the patients were divided into three groups ,the mild group (5/h ≤ AHI < 15/h) with 31 cases ,the moderate group (15/h ≤ AHI < 40/h) with 36 cases ,and the severe group (AHI ≥ 40 /h) with 41 cases . The levels of blood pressure were compared among the groups . According to whether OSAHS was accompanied by hypertension ,the patients were divided into simple OSAHS group and OSAHS accompanied by hypertension group . The relevant factors associated with OSAHS accompanied by hypertension were screened out by single factor analysis ,and then the multiple Logistic regression analysis was conducted .Results : (1)Among 108 patients with OSAHS ,60 cases(55 .6% ) were accompanied by hypertension ,including 15 cases of mild group(48 .4% ,15/31) ,19 cases of moderate group (52 .8% ,19/36) ,and 26 cases of severe group (63 .4% ,26/41 ) . There was no significant difference regarding the prevalence rate of hypertension among the three groups (P > 0 .05) .There were significant differences regarding systolic blood pressure(SBP) and diastolic blood pressure (DBP) at 22 ∶ 00 and 8 ∶ 00 among the three groups (P < 0 .05) ;SBP and DBP at 22 ∶ 00 and 8 ∶ 00 in severe group were significantly higher than those in mild group (P< 0 .05) .SBP at 22 ∶ 00 and 8 ∶ 00 in severe group was significantly higher than that in moderate group (P< 0 .05) .(2) Single factor analysis showed that age ,body mass index (BMI) ,smoking rate ,abdominal circumference ,AHI ,total cholesterol(TC) ,triglyceride(TG ) and low density lipoprotein cholesterol (LDL-C) in OSAHS accompanied by hypertension group were significantly higher than those in simple OSAHS group ,while HDL-C was significantly lower than that in simple OSAHS group ( P < 0 .05 ) . (3 ) Multivariate Logistic regression analysis showed that BMI ,AHI ,TC were the risk factors for OSAHS accompanied by hypertension .Conclusions :The level of blood pressure in patients with OSAHS was accordance with the disease severity ,while BMI ,AHI ,TC were the risk factors for OSAHS accompanied by hypertension .