A 78-year-old male presented to the Emergency Department complaining of a 1-week onset of increasing fatigue and anorexia. The patient was previously well but had a history of depression, chronic diarrhea, and hypertension. His examination was remarkable for mild fever (100.1°F). He had no acute neurologic deficits. The patient felt better after intravenous fluids and was discharged to follow-up with the primary care provider. With no resolution of symptoms and new memory loss, the patient's primary care doctor ordered an MRI which revealed abnormal signal/patchy enhancement of the left temporal lobe indicative (pathognomonic) of herpes simplex encephalitis. This case emphasizes the importance of early consideration of herpes simplex encephalitis in the differential of patient's with these symptoms.