The aim of this phase II, randomized, double-blind clinical trial is to evaluate the effect of home-based transcranial direct current stimulation (tDCS) in patients with treatment-resistant depression. Major depressive disorder is defined by depressed mood and/or loss of interest in activities, during most of the day, nearly every day, for at least two weeks. It is usually accompanied by other symptoms, such as fatigue, sleep disturbances, thoughts of guilt, suicidal ideation, appetite alterations, difficulty to focus and physical agitation or retardation. It is estimated that its worldwide prevalence is 5%, affecting 280-300 million people. A third of patients with depression will develop treatment resistant depression, where symptoms fail to remit after at least two trials of antidepressants. Beyond psychotropics, another treatment option is neuromodulation, where excitatory or inhibitory signals are delivered to the brain, in order to modulate cortical excitability. The tDCS is a non-invasive brain stimulation method that applies a low intensity direct current (1-2mA) directed to the scalp via the cathode and anode electrodes. The current reaches the cortex, facilitating hyperpolarization or depolarization of the axonal membrane potential. Evidence has shown that this method is presented as a technique able to alter cortical and subcortical neural networks. This technique has been used to treat psychiatric disorders such as depression, bipolar affective disorder, panic, hallucinations, obsessive compulsive disorder, schizophrenia, withdrawal, rehabilitation after stroke and pain syndromes such as neuropathic pain, migraine and fibromyalgia. It has a low cost and less side effects than psychotropic medications. In order to be effective, daily repeated sessions of 20-40 minutes are necessary. When applied in a hospital setting, this frequency of sessions can limit its appliance, especially for depressed patients, whose symptoms include fatigue and loss of interest in activities. Furthermore, transportation costs, frequent absences from work and other activities and overload of the healthcare system would also limit its use. Home based devices are portable and easily operated. Thus, it is possible for patients to administer themselves the treatment, in their own home, everyday. Therefore, the aim of this study is to evaluate the effect of home-based tDCS in treatment resistant depression patients in long-term treatment.