: Transcranial magnetic stimulation is a neurophysiological method which enables direct quantitative in vivo assessment of cortical excitability and inhibition. The aim of the study was to assess the impact of paliperidone on the motor threshold and cortical silent period, in a drug-naive patient, with first episode schizophrenia using this technique. Paliperidone monotherapy caused a significant reduction of severity of schizophrenic symptomatology in the patient. At the same time, a significant prolongation of the cortical silent period, from 118.68 ms before to 185.13 ms after therapy, occurred. Because the cortical silent period is a function of GABA(B) receptors, we can assume that paliperidone may have the ability to enhance GABA(B) receptor-mediated neurotransmission.