- Background Repetitive deep transcranial magnetic stimulation (dTMS) is efficacious for treatment resistant major depressive disorder (TRD) with the H1 coil by stimulating the prefrontal cortex, left more than right, at high frequency. Theoretically, the efficacy of dTMS could be optimized by simultaneously stimulating the right and left lateral prefrontal cortices (PFC) with different frequencies. This study tested the efficacy of a novel dual-channel dTMS stimulator with dual dTMS coils, in patients with TRD. Methods This study recruited forty-seven outpatients diagnosed with TRD, age 18-65, Hamilton Depression Rating Scale (HDRS-21) score ≥25. Each patient received 20 open label treatment sessions, five days a week for 4 consecutive weeks. Treatments were administered with the dual-channel stimulator (Brainsway Multiway dTMS device) using two channels: a. 10 Hz over the left PFC. b. 1 Hz over the right PFC. Primary and secondary efficacy outcome measures were the change in HDRS-21 score and response/remission rates at week 5, respectively. Results The HDRS-21 score decreased from an average of 25.94 to 14.69 (P Discussion This open study shows promising results for multichannel simultaneous dTMS treatment of TRD using the Brainsway Multiway Device. Further randomized controlled studies are necessary to aid the high number of patients with TRD. Funding Acknowledgements Brainsway Ltd.