A method of and system for monitoring a patients EEG (electroencephalogram) during TMS (Transcranial Magnetic Stimulation) are disclosed. The system comprises a TMS device to generate, when in an active state, a plurality of magnetic pulses, which can be applied either as a burst, comprising a plurality of pulses grouped together, or as individual pulses, to the patients head, in accordance with a TMS treatment protocol. An EEG system is provided to measure EEG data resulting from the TMS treatment protocol being applied to the patient. The system further comprises control means in communication with the TMD device and the EEG system, the control means being arranged to activate the EEG system during the time periods when the TMS device is not generating pulses, such that the EEG data measurement is continuously applied or interleaved with the magnetic pulses being generated in accordance with the TMS treatment protocol, so as to monitor treatment efficacy and detect potential seizures.
