The authors present a case of environmentally acquired fatal herpes virus type I infection in a newborn after cesarean section and a discussion of the clinical presentation, pathogenesis and diagnosis of herpes simplex type I (HSV-1) at autopsy. Herpes simplex virus, both type I and type II, are well described infectious agents in newborns. Though herpes simplex type II (HSV-2) is commonly associated with fatal neonatal infections, it is important to consider HSV-1 to make the correct diagnosis. Additionally, although HSV infections are typically acquired during parturition, it is possible to be infected postpartum from the environment as occurred in this case. The diagnosis of neonatal HSV must also be communicated by the forensic pathologist to applicable healthcare providers and health care facilities, because of public health and medicolegal issues. Copyright © 2010 by Lippincott Williams & Wilkins.