en General پژوهشي Research Article Background: The metabolic syndrome is associated with increased risks of cardiovascular diseases and diabetes mellitus.Objectives: As alternative medicine emerged worldwide, this study aimed to evaluate the efficacy of Berberis vulgaris (barberry fruit) in the treatment of metabolic syndrome.Methods: This is a randomized, placebo controlled, double-blind, trial with two treatment arms. A total of 60 patients with metabolic syndrome were randomly assigned to receive barberry or placebo tablets (one 550 mg tablets per day for 3 weeks). Total cholesterol, LDL, HDL, triglyceride, fasting blood sugar and hematocrit were measured before and after 21 days of treatment. Data were analyzed using Mann-Whitney U and paired t-test by SPSS (V.15) software. P-values < 0.05 were considered to be significant.Results: In the barberry group, there was a significant decrease in systolic blood pressure (pre-treatment 123.1 &plusmn; 13.1 vs. post-treatment 117.7 &plusmn; 13.2, P-value = 0.04), waist circumference (pre-treatment 105.9 &plusmn; 7.5 vs. post-treatment105 &plusmn; 7.7, P-value = 0.04) and hematocrit (pre-treatment 45 &plusmn; 3.6 vs. post-treatment 43.5 &plusmn; 2.7, P-value = 0.004) but other parameters did not change significantly. Serum cholesterol was significantly reduced after intervention in the barberry group (-17 &plusmn; 61.1 vs. 23.6 &plusmn; 45, P-value = 0.02).Conclusions: We observed a significant effect of barberry on systolic blood pressure and waist circumference. Further studies with larger samples are needed to longitudinally investigate the effect of metabolic syndrome. Metabolic Syndrome,Hematocrit,Berberisl,Random Clinical Trial 0 0 http://mcj.bums.ac.ir/browse.php?a_code=A-10-1-144&slc_lang=en&sid=1 Tayyebeh Kermani 10031947532846002018 10031947532846002018 No Cardiovascular Disease Research Center, Birjand University of Medical Sciences, Birjand, Iran Toba Kazemi 10031947532846002019 10031947532846002019 Yes Cardiovascular Disease Research Center, Birjand University of Medical Sciences, Birjand, Iran. Email: drtooba.kazemi@gmail.com Somayye Molki 10031947532846002020 10031947532846002020 No Student Research Committee, Birjand University of Medical Sciences, Birjand, Iran Khadije Ilkhani 10031947532846002021 10031947532846002021 No Student Research Committee, Birjand University of Medical Sciences, Birjand, Iran Gholamreza Sharifzadeh 10031947532846002022 10031947532846002022 No Infectious Diseases Research Center, Birjand University of Medical Sciences, Birjand, Iran