Depression is the leading cause of disability worldwide. We recruited patients with major depressive disorder who had not responded to antidepressant medication, to test the antidepressant efficacy of a novel treatment called Stanford Neuromodulation Therapy compared to sham treatment. The active protocol was more effective than sham treatment. After the 5-day active treatment, 79% of patients no longer met clinical criteria for depression compared to only 13% in the sham group. Our accelerated, high-dose neuromodulation protocol appears more effective than existing treatments in this population; however, head-to-head trials with other treatments are needed. The short 5-day duration and high antidepressant efficacy of this treatment means that it could be a particularly valuable treatment for patients in hospital settings where fast, effective treatments are needed.