An inguinal lymph node was excised from a 23-year-old woman. Histologic examination revealed necrotic foci with cytologic changes indicative of herpes simplex virus; immunohistochemistry and electron microscopy confirmed the presence of virus. Typical cutaneous lesions appeared on the vulva three days after surgery. Focally necrotizing lymphadenitis and cytologic changes of viral transformation are unusual in herpes group infections.