The purpose of this study is to assess the effectiveness of transcranial direct current stimulation (tDCS) in relieving pain of patients with fibromyalgia. Eligible participants will be randomly assigned to one of the two groups: Group I (Intervention group) tDCS (2mA for 25 minutes on 5 consecutive days/week for 2 weeks with the anode centered over M1 bilaterally Anodal tDCS for 20 minutes at 1.5 mA (15 s ramp in and 15 s ramp out) will be applied daily for 10 consecutive days (5 sessions/week) . The anodal electrode (24 cm² with current density of 0.08 mA (2mA/24 cm²) will be placed over the left primary motor area in group I, and the reference electrode (24 cm² will be fixed over the contralateral arm (extracephalic).