BD represents the greatest burden on patients with bipolar disorder, since the depressive episodes are the most frequent and also particularly associated with suicide 7. BD treatment is controversial, with some stricter guidelines recommending only lithium, lamotrigine and quetiapine as a first-treatment, whereas others allow the use of antidepressants (which can increase manic switch and should be used in association with mood stabilizers) and other anticonvulsants and antipsychotics 8. For refractory BD the available level I evidence is very scarce, with only seven studies exploring this issue hitherto 9. Therefore, the importance of this study proposal is justified considering the burden of the disease, the paucity of current therapeutic studies and the promising results presented for tDCS in unipolar disorder.