en General پژوهشي Research Article Background:&nbsp;Apelin, an adipokine secreted from adipose tissue, plays an important role in regulating blood pressure and hypertension.Objectives:&nbsp;The current study aimed to compare the plasma Apelin level in hypertensive patients under treatment with amlodipine, losartan, and amlodipine + losartan.Methods:&nbsp;In this case-control study, the serum level of Apelin was compared in four groups of (A) Healthy subjects (n = 31); (B) Hypertensive patients, received amlodipine (n = 31); Hypertensive patients, received losartan (n = 45); and patients (n = 33) that received amlodipine and losartan. Apelin level in serum samples was measured using Human Apelin ELISA Kit according to the manufacturers&rsquo; instructions. Data were analyzed using SPSS version 19 (Chicago: SPSS Inc.), at the significant level of &alpha; = 0.05.Results:&nbsp;The mean blood level of Apelin in the control group and groups receiving amlodipine, losartan, and amlodipine + losartan was 366.16 &plusmn; 36.04, 247.19 &plusmn; 27.77, 282.93 &plusmn; 47.08, and 289.84 &plusmn; 32.20 g/dl, respectively. Losartan + amlodipine group had a higher level of Apelin compared with amlodipine alone (P < 0.05).Conclusions:&nbsp;This study demonstrated that Apelin has a definite protective effect in preventing hypertension. Also, according to the results, the renin-angiotensin-aldosterone system inhibitors, such as losartan, caused a higher increase in the Apelin, resulting in better blood pressure control. Hypertension,Losartan,Amlodipine,Apelin,Calcium Channel Blocker Receptor,Angiotensin II Receptor Antagonists 0 0 http://mcj.bums.ac.ir/browse.php?a_code=A-10-1-164&slc_lang=en&sid=1 Mina Hemmati 10031947532846001975 10031947532846001975 Yes Biochemistry Department, Zanjan University of Medical Sciences, Zanjan, Iran Fatemeh Abharzanjani 10031947532846001976 10031947532846001976 No Student Research Committee, Birjand University of Medical Sciences, Birjand, Iran Tooba Kazemi 10031947532846001977 10031947532846001977 No Cardio Vascular Diseases Research Center, Birjand University of Medical Sciences, Birjand, Iran Fateme Estanesti 10031947532846001978 10031947532846001978 No Faculty of Medicine, Birjand University of Medical Sciences, Birjand, Iran