Chlamydial infection is the most common bacterial sexually transmitted infection in Sweden and worldwide, despite extensive testing, efficient treatment and partner notification. The incidence of Lymphogranuloma venereum, currently occurring among men who have sex with men and most often in the rectum, shows no tendency to decline. This infection is usually symptomatic but still evading diagnosis due to similarities to other causes of proctitis. There is evidence that rectal chlamydia is common also in women not practicing anal sex.