Investigators have suggested that innocuous somatosensory input is processed serially from the thalamus to the primary somatosensory cortex (S1) and then to other brain regions; whereas nociceptive input would project in parallel from the thalamus to S1 and other brain regions. Here, we test this hypothesis by assessing the effect of High-definition transcranial direct current stimulation (HD-tDCS) applied to the left S1 on the perception and event-related potentials (ERPs) elicited by nociceptive and non-nociceptive stimuli delivered to the ipsilateral and contralateral hand. HD-tDCS was achieved using a cathode surrounded by four anodes (20 minutes; 1 mA). Nociceptive stimuli were pulses of radiant heat delivered to the hand dorsum. Non-nociceptive stimuli were short-lasting vibrations delivered to the index. Nociceptive and non-nociceptive ERPs were recorded immediately before and after HD-tDCS. After each stimulus, participants rated intensity of perception. Because HD-tDCS was expected to reduce the excitability of the left S1, we expected that the responses to non-nociceptive stimulation of the contralateral hand would be reduced as compared to the ipsilateral hand. Furthermore, we predicted that the responses to nociceptive stimulation of the contralateral hand would show a similar reduction if and only if S1 constitutes an obligatory relay for nociceptive input.