Chlamydia trachomatis (C. trachomatis) infection is a bacterial sexually transmitted infection (STI) that is most often asymptomatic but, if left untreated, can lead to ectopic pregnancy and tubal infertility. Given the severity of these complications, recommendations for screening for this infection in asymptomatic individuals exist in several countries. In France, the National Agency for Accreditation and Evaluation in Health (Anaes) considers that systematic screening for urogenital C. trachomatis infections is warranted in certain healthcare settings. Diagnosis of C. trachomatis infection is made through a direct identification test on a genitourinary specimen. The positivity rate (number of positive cases/number of individuals tested in a laboratory) serves as an indicator of the epidemiological situation of this infection, which is endemic in France. Through the Rénachla network of medical laboratory testing facilities, which collects information on individuals who have tested positive via direct identification, as well as the total number of C. trachomatis tests performed in men and women, it is possible to estimate the overall positivity rate in men and women. Since Rénachla does not have information on individuals with negative results, it is not possible to calculate positivity rates based on certain parameters such as the age of the tested subjects. This article presents the survey conducted in 2001 among Rénachla laboratories to calculate positivity rates by age and sex and according to patients’ places of consultation, in order to identify the places of consultation where these rates are highest. (R.A.)