Objective :To study influence of valsartan combined hydrochlorothiazide on 24h diastolic blood pressure (DBP) ,24h systolic blood pressure (SBP) and blood pressure variability (BPV) in patients with hypertension .Meth—ods : A total of 94 hypertensive patients treated in our hospital were randomly and equally divided into valsartan group and combined treatment group (received valsartan combined hydrochlorothiazide ) ,both groups were treated for one month .The 24hDBP ,24hSBP ,BPV ,levels of nitric oxide (NO ) and endothelin (ET ) before and after treatment and incidence of adverse reactions were compared between two groups .Results : Compared with valsartan group after treatment ,there were significant reductions in 24hSBP [ (130. 64 ± 10.01) mmHg vs .(121.53 ± 9.35) mmHg] ,24h DBP variability (24hDBPV) [ (12.47 ± 3.32)% vs.(10.82 ± 2.71)%] ,24hSBPV [ (10. 42 ± 2. 00)%vs.(8.51 ± 1. 64)%] and daytime SBPV [ (10.87 ± 2. 05)% vs.(8. 66 ± 1.65)%] , P＜0. 05 or ＜0.01 ;significant rise in NO level [ (42.92 ± 6.84) μmol／L vs.(53.43 ± 7. 16) μmol／L] and significant reduction in ET level [ (38. 62 ± 5.52) ng／L vs .(31. 01 ± 5. 01) ng／L] in combined treatment group , P＝0.001 both .There were no significant difference in incidence of adverse reactions between two groups , P＞ 0.05 all.Conclusion : Valsartan combined hydrochlorothiazide can effectively improve levels of 24hDBP ,24hSBP and blood pressure variability ,and contrib— ute to regulating NO and ET levels in patients with hypertension .