In July 2000, an amendment to the Public Health Code lifted the requirement to report sexually transmitted diseases (Ordinance 2000-548 of June 15, 2000). In late November 2000, a resurgence of syphilis was documented, leading to the establishment of a surveillance system. The objectives of this system are to monitor, in participating centers, the annual trend in the number of adults with syphilis and to describe their clinical, biological, and behavioral characteristics. The 2000–2002 surveillance data have been published; this report includes the 2003 data.