This pamphlet reviews the hazards posed by this very common and incurable infection, whose occurrence is increasing among gay men. It stresses that 45% of infected people do not know that they have the disease because it produces only transitory symptoms. It describes the two types of herpes simplex virus, the four stages of infection, and the symptoms and/or risks with each stage. Readers are warned that herpes infection significantly increases the risk of receiving or transmitting the HIV virus. Those seeking further information are referred to the “In the Know Zone” website and to the National STI Hotline.