Herpes simplex virus (HSV) encephalitis is an infectious disease emergency with potential for significant patient morbidity and mortality. Although lumbar puncture, computed tomography, and magnetic resonance imaging (MRI) remain useful diagnostic modalities in the diagnosis of HSV encephalitis, clinical signs prompting providers to obtain these studies are often nonspecific. The diagnosis requires a high index of suspicion, and the importance of a thorough history and physical examination cannot be overemphasized. We present a case of HSV encephalitis presenting with unilateral piloerection as the sole manifestation on physical examination, a finding that is most likely explained by neuronal excitation in the temporal lobe. In 2004, a published case series addressed the localizing and lateralizing value of piloerection during seizures. The authors concluded that ictal piloerection is predominately seen in patients with temporal lobe seizure foci and does not appear to correlate with laterality . This finding dovetails with the characteristic pattern of temporal and insular lobe edema seen on MRI in patients with HSV encephalitis . The associated focal piloerection seen in our patient is likely attributable to neuronal hyperexcitation of his left or right mesial temporal lobe given the MRI findings. To the best of our knowledge, an association of focal piloerection or focal pilomotor seizure activity with acute HSV encephalitis has not been published. We present a case in which detection of this subtle feature prompted timely brain imaging and ultimately led to the diagnoses and timely treatment of HSV encephalitis.