Trancranial Magnetic Stimulation (TMS) is a non-drug and non-invasive treatment for depression and has been investigated for the treatment of psychiatric illness for over 15 years. There is now established evidence indicating TMS is an effective treatment for depression. However, the effectiveness of TMS varies between people, thus requiring further research to investigate its optimal application. Investigators want to compare the effectiveness of different forms of TMS, given with differing stimulation settings to the right or left side of the brain that has been associated with depression. This could potentially help clinicians in the future to improve the prescription of TMS as a treatment for depression.

Inclusion Criteria:

1. Age ≥18 years.
2. DSM-IV diagnosis of current Major Depressive Episode.
3. MADRS score of 20 or more.
4. Able to give informed consent.

Exclusion Criteria:

1. DSM-IV psychotic disorder.
2. Drug or alcohol abuse or dependence (preceding 3 months).
3. Inadequate response to ECT (current episode of depression).
4. Rapid clinical response required, e.g. high suicide risk.
5. Significant neurological disorder, which may pose increased risks with TMS, e.g., epilepsy.
6. Metal in the cranium, skull defects, pacemaker, cochlear implant, medication pump or other electronic device.
7. Pregnancy.