Transcranial electric motor evoked potentials (TCeMEPs) are routinely used intraoperatively to detect and prevent iatrogenic injury to the spinal cord, specifically the corticospinal tract. Complications related to TCeMEP testing include the potential for seizure induction, cardiac arrhythmia, scalp burns, infection, and tongue or lip laceration. Among this list of potential complications, tongue and lip lacerations are the most common and most directly attributable to transcranial stimulation. The technique of low voltage stimulation and the correct placement of oral bite blocks is successful in preventing patient bite injuries. We report two cases of patient bite injuries following TCeMEPs and discuss potential mechanisms of injury and prevention.