The present study is a randomized double-blinded placebo-controlled clinical trial aimed to investigate the effects of brewed tea of poulk (Stachys Schtschegleevii) on some biochemical parameters and disease activity in women with rheumatoid arthritis. Patients will be recruited from the rheumatology clinics of Tabriz University of Medical Sciences, Tabriz, Iran. After giving written informed consent, 42 female RA patients who met the inclusion criteria will be included in the study. Then, they will be randomly assigned 1:1 to two groups to receive either the main intervention (2.4 gram of poulk with 2.4 gram of black tea) or placebo (2.4 gram of black tea) for 8 weeks (2 times a day, after lunch and dinner, each time the dried herbal powder in 240 ml boiled water, with brewing time of 20 minutes). At the beginning of the study demographic data (including age, disease history, educational status, etc) will be collected. Anthropometric parameters (height, weight, body mass index, waist and hip circumferences), disease activity (based on disease activity score in 28 joints) and serum biomarkers (intelukin-1, tumor necrosis factor-alpha, high sensitive-c reactive protein, matrix metalloproteinase-1 and matrix metalloproteinase-3) will be evaluated at baseline and after 8 weeks. Moreover, at initial and final points, physical activity level and dietary intake are assessed using the international physical activity questionnaire and a three-day dietary record respectively. Finally, biochemical, clinical, anthropometric and dietary data will be analyzed.