H erpes simplex virus is the most common virus causing oral infections. There are two types of herpes simplex viruses, type 1 and type 2. Type 1 commonly produces oral disease called primary herpetic gingivostomatitis. Type 2 causes lesions on the genital area. Herpes simplex virus will not disappear after primary infection, but becomes latent in the trigeminal ganglion. Predisposing factors may trigger the virus, reactivate it and produce infection of the oral cavity. The pathogenesis of herpes simplex virus began when the virus enters the body and attack the cell. Then the cell becomes necrotic and forms a ballooning degeneration. Along with it, multinucleated giant cells and inclusion bodies called Lipschutz bodies are also found.