This randomized, double-blind, controlled clinical trial compared the effectiveness of home-based-(HB) active transcranial direct current stimulation (a-tDCS) over the left dorsolateral prefrontal cortex (l-DLPFC) or primary motor cortex (M1) with their respective sham-(s)-tDCS to determine whether a-tDCS would be more effective than s-tDCS in reducing pain and improving disability due to pain. The study included 102 patients with fibromyalgia aged 30 to 65 years old randomly assigned to one of four tDCS groups using a ratio of 2:1:2:1. The groups included l-DLPFC (a-tDCS, n=34) and (s-tDCS, n=17), or tDCS on the M1 (a-tDCS, n=34) or (s-tDCS, n=17). Patients self-administered 20 sessions of tDCS, with 2mA for 20 minutes each day under remote supervision after in-person training. The mixed model (MMRM) revealed that a-tDCS on DLPFC significantly reduced pain scores by 36.53% compared to 25.79% in s-tDCS. From baseline to the fourth week of treatment, a-tDCS on M1 reduced pain scores by 45.89% compared to 22.92% over s-tDCS. A generalized linear model showed a significant improvement in the disability scale in the groups that received a-tDCS compared to s-tDCS over M1 20.54% versus 2.49% [χ2=11.06, Df=1, P<0.001)], while on DLPFC the improvement was 14.29% and 5.77%, with a borderline significance [χ2= 3.19, Df=1, P=0.06)], respectively. A higher reduction in serum brain-derived neurotrophic factor (BDNF) from baseline to treatment end was positively correlated with decreased pain scores regardless of the treatment group. The application of a-tDCS over M1 increased the heat pain threshold and the function of the descending pain inhibitory system. PERSPECTIVE: These findings provide important insights: (i) HB-tDCS has effectively reduced pain scores and improved disability due to fibromyalgia. (ii) The study provides evidence that HB-a-tDCS is a viable and effective therapeutic approach. (iii) HB-a-tDCS over M1 improved the function of the DPIS and increased the heat pain threshold. Finally, our findings also emphasize that BDNF, as an index of neuroplasticity, may serve as a valuable marker associated with changes in clinical pain measures.Copyright © 2023. Published by Elsevier Inc.