The herpes simplex viruses type 1 and 2 (HSV 1 and 2) as typical members of the larger herpes virus group have the tendency to become latent after an inapparent primary infection. They are transmitted from person to person during episodes of reactivation. HSV 1 and 2 usually cause harmless mucosal infections. Usually HSV are kept in check by the immune system. An impaired immune response leads to HSV infections which can be life-threatening. Genital HSV infections are an important cause of genital ulcerations, and HSV 2 is a predisposing factor for HIV and AIDS. Worldwide the diagnostic possibilities for HSV are often inadequate. Despite the availability of modern chemotherapeutic agents, the treatment of HSV infections is in many cases less than satisfactory. Dermatologists play a major role in the early diagnosis and effective therapy of these infections. In this paper, the latest diagnostic and therapeutic, as well as prophylactic measures and vaccines, are reviewed.