This study is looking at the safety and efficacy of low field magnetic stimulation (LFMS) for treating patients with treatment resistant depression who are taking an antidepressant that is not working for them.

Inclusion Criteria:

• Male or female, 18-65 years old
• Diagnosed with Major Depressive Disorder (MDD) and currently experiencing a Major Depressive Episode (MDE) of at least eight weeks
• A participant has Treatment Resistant Depression (TRD) of the current MDE
• Good general health
• For female participants, status of non-childbearing potential or use of an acceptable form of birth control
• Body mass index between 18-40 kg/m2
• Concurrent psychotherapy will be allowed if the type and frequency of the therapy has been stable for at least three months prior to screening and is expected to remain stable during participation in the study
• Concurrent hypnotic therapy will be allowed if the therapy has been stable for at least 4 weeks prior to screening and is expected to remain stable during the subject's participation in the study
• Participant must be able to lie flat for 20 minutes

Exclusion Criteria:

• A woman of childbearing potential who is not willing to use one of the specified forms of birth control during the study

• Pregnant or breastfeeding

• A woman with a positive pregnancy test at screening or baseline

• Participant has TRD of the current MDE with failure to achieve a satisfactory response, as perceived by the subject, to more than 3 treatment courses of a therapeutic dose of an antidepressant therapy of at least eight weeks duration

• Participant has a current diagnosis of a Substance Use Disorder with the exception of nicotine dependence, at screening or within six months prior to screening

• Current diagnosis of Axis I disorders other than Generalized Anxiety Disorder, Social Anxiety Disorder, Panic Disorder, Specific Phobia, Post Traumatic Stress Disorder or Complicated Grief (unless one of these is comorbid and clinically unstable, and/or the focus of the participant's treatment for the past six months or more).

• Subject has a history of schizophrenia or schizoaffective disorders, any history of psychotic symptoms or is on antipsychotic medication for the treatment of psychotic symptoms

• Subject has a history of eating disorders within five years of screening

• Subject has any Axis I or Axis II Disorder, which at screening is clinically predominant to their MDD or has been predominant at any time within six months prior to screening

• The participant is considered at significant risk for suicide during the study

• Subject has had electroconvulsive therapy in the current episode of depression

• Subject has had Transcranial Magnetic Stimulation or has received treatment with other experimental devices for the treatment of the current episode of depression

• Subject has received Vagus Nerve Stimulation at any time

• Dementia, delirium, amnestic, or other cognitive disorders

• There is a clinically significant abnormality on the screening physical examination

• Participation in any clinical trial with an investigational drug or device within the past month or concurrent to study participation

• Known history or current episode of:

  --Uncontrolled hypertension, Recent myocardial infarction (within one year) or a history of more than one myocardial infarction, Syncopal event within the past year, Congestive heart failure, Angina pectoris

• Lifetime history of surgical procedures involving the brain or meninges, encephalitis, meningitis, degenerative central nervous system disorder (e.g., Alzheimer's or Parkinson's Disease), epilepsy, mental retardation, any other disease/procedure/accident/intervention associated with significant injury to or malfunction of the central nervous system, or a history of significant head trauma within the past two years.

• Lab abnormalities are present

• History of hypothyroidism and has been on a stable dosage of thyroid replacement medication for less than six months prior to screening

• Hisotry of hyperthyroidism which was treated (medically or sugically) less than six months prior to screening

• Any current or past history of any physical condition which in the investigator's opinion might put the subject at risk or interfere with the interpretation of study results

• History of positive screening urine test for drugs of abuse

• Patient with any non-removable stimulation device such as neurostimulators, pacemakers and cochlear implants

• Patients requiring treatment with excluded concomitant medications

• Patients who cannot be in a MRI

• Patients who are currently using a metal intrauterine device (IUD)