Transcranial magnetic stimulation is a non-invasive, painless diagnostic tool of nervous propagation as well as of motor cortex excitability in healthy subjects and in patients affected by several neurological disease ie, stroke, epilepsy and multiple sclerosis etc. Motor areas can be reliably mapped and short-and long-term 'plastic' changes of neural connections can be studied and monitored over time. Recent studies suggest a therapeutic role of repetitive magnetic stimulation in neurologic and psychiatric disorders.