RENACHLA (National Network for Chlamydial Infections) is a national network of clinical laboratories established in 1989 for the epidemiological surveillance of urogenital chlamydial infections in France. The laboratories participating in the network report monthly to the National Public Health Network (RNSP) the number of tests for Chlamydia trachomatis performed by direct examination. For each detected case, the following information is provided: the patient’s age and sex, the clinical signs observed, associated pathogens, the prescriber’s qualifications, and the reasons for the prescription. RENACHLA laboratories account for 2.8% of all French laboratories capable of identifying C. trachomatis in metropolitan France. In 1997, the laboratories analyzed 55,000 specimens, 77% of which were collected from women. A total of 1,502 Chlamydia trachomatis cases were identified, including 986 in women and 513 in men. While the number of C. trachomatis cases identified per laboratory continues to decline among women, the number of C. trachomatis cases identified among men increased by 17% from 1996 to 1997. At the same time, there has been an increase in the number of samples collected from men. (adapted from the text).