Objectives. To assess the effectiveness of transcranial direct current stimulation (tDCS) for pain, fatigue, physical function, and health-related quality of life in patients with idiopathic inflammatory myopathy (IIM). Methods. This randomized, double-blind, sham-controlled, crossover clinical trial enrolled IIM patients with fatigue and pain who received tDCS (20 min, 2 mA) or sham stimulation for 10 daily sessions. Electrodes were placed according to the 10/20 EEG system. Both the groups underwent aerobic exercise training during the intervention period. The patients were evaluated for disease perception, pain, and fatigue using uni-multidimensional questionnaires and physical tests in the periods before and after the first and second interventions and after 12 weeks of follow-up. Results. After the tDCS intervention, a reduction in the general score of multidimensional pain of 32.0 (1.5-38.0) vs. 0.0 (0.0-13.4) with effect size (ES) of -0.78 was noted, and after sham intervention, a reduction of 26.0 (0.0-37.0) vs. 5.0 (0.0-19.2) with ES of -0.54 (P=0.047) was also noted. Similar results were evidenced with fatigue (22.5 (15.4-33.2) vs. 5.5 (0.0-14.6) with ES of -0.82) and sham intervention (21.0 (15.8-29.5) vs. 4.0 (4.0-17.5) with ES of -0.80 (P=0.012)). There were no differences in the domains of the fatigue and pain questionnaires. Adherence was observed in 88.8% of the patients without adverse events. Conclusion. The association of tDCS with aerobic training promoted additional effects in relation to the group subjected to placebo stimulation on general pain and fatigue scores, as well as on pain intensity, without changes in the subdomains of the pain and fatigue questionnaire. This trial is registered with NCT04678635.