Sexually transmitted diseases (STD) are a major public health problem because their incidence is increasing worldwide despite prevention campaigns and because they raise the risk of HIV infection. Anorectal localisations of STD are common among men who have sex with men (MSM) but can also be seen among heterosexuals (men or women). Transmission of such infections is due to anal sex or to other sexual behaviours like "fisting". Although some pathogens (like Human Papillomavirus-HPV) are common in gastroenterologist/proctologist consultations, others are not so well-known. Furthermore during the last years, sexual risky behaviours have led to resurgence of old affections (like syphilis) or to emergence of unknown diseases (like lymphogranuloma venereum) in our countries. This presentation tends to focus on clinical manifestation, diagnosis and treatment of different STD: HPV, Herpes Simplex Virus, Neisseria gonorrhoeae, Chlamydia trachomatis (in particularly lymphogranuloma venereum) and Treponema pallidum.