Sexually transmitted diseases frequently affect the mucous membranes producing characteristic and potentially diagnostic lesions on the oral mucosa. This article reviews the classic route of transmission and the corresponding clinical presentation of several of the sexually transmitted viruses, including herpes virus types I and II, Epstein Barr virus, cytomegalovirus, human papilloma virus, molluscum contagiosum, as well as the human immunodeficiency virus. Bacterial infections such as syphilis, gonorrhea, as well as the fungus candida are reviewed under the umbrella of STDs with potential oral involvement encountered in the sexually active patient.