Introduction and Objectives: Surveillance of Chlamydia trachomatis anorectal infections through a network of clinicians and laboratory professionals in France. Materials and Methods: Molecular typing of genital and anorectal samples sent to the CNR and collection of clinical, laboratory, and behavioral data. Results: Since 2004, the number of LGV cases typed at the CNR has reached 1,791, and the number of anorectal infections caused by non-L strains has reached 1,284. The epidemiological trend for LGV cases shows a sharp increase in 2013 (102 in 2004, 318 in 2013). LGV cases are more frequently identified in Paris (75.25%) than in the provinces (p < 0.05). C. trachomatis anorectal infections affect men who have sex with men and who have casual partners. Only one female case was reported. LGV differs from non-L-strain anorectal infection in its symptomatic nature (p < 10⁻⁷) and its association with HIV (p < 10⁻⁸). The association with syphilis is higher in the LGV group (32.2% vs. 21%, p < 0.05). In contrast, the association with Neisseria gonorrhoeae is higher in cases of non-L-strain anorectitis (28% vs. 19.6%, p < 0.05). The number of cases of non-L-strain anorectitis also increased between 2004 (26 cases) and 2013 (392 cases). Analysis of serovar distribution shows that serovars D (35.2%), G (29.5%), and J (17.3%) are the most common, whereas serovar E, which is predominant in genital specimens, accounts for only 10.3% of anorectal infections. Conclusion: Regular typing of genital strains shows that LGV has not yet spread to the general population. LGV remains primarily anorectal; only 42 cases of genital LGV with ulceration and inguinal lymphadenopathy and 5 cases of pharyngeal carriage have been identified. Surveillance must continue as the epidemic is still spreading. (R.A.)