Orogenital sex in the last decades has become a common sexual practice (fellatio and cunnilingus) between both heterosexual and homosexual individuals. Consequently, several sexually transmitted diseases (STDs) including bacterial infections, are a persistent problem in Europe and throughout the world, despite vigorous efforts in prevention and people education. The last two decades, HIV infection, revived the interest of the medical community and the people for the sexually transmitted diseases. Many of these bacterial infections present predominantly with characteristic oral signs and symptoms. As a result, it is imperative for the oral physician (stomatologist) to keep abreast of the latest updates in the behavior and to be aware of the whole spectrum of clinical manifestations of these diseases. Orogenital bacterial infections may be divided into two major categories: (i) Common including syphilis and gonorrhoea and (ii) Rare, including chlamydia trachomatis infection and tropical sexually transmitted infections (chancroid, donovanosis, lymphogranuloma venereum). Syphilis is the leader of sexually transmitted diseases and has been of great interest in the past and today and has played a central role in medicine for several decades. The oral lesions of syphilis (primary secondary and tertiary stages) have a broad spectrum of manifestations, which mimic a lot of other oral lesions. The recent incidence data, the oral manifestations, the laboratory tests and treatment of both categories of these diseases will be discussed, as the increased practice of oral sex has become a more important potential route of transmission for oral and genital bacterial pathogens. Stomatologists and Dentists, frequently evaluate oral mucosal manifestations and thus play an important role in the diagnosis and treatment of many of highly infectious sexually transmitted infections.