Objectives: The objective of this paper is to provide a detailed description of Internet-based sexually transmitted disease/human immunodefieiency virus prevention in the 8 US cities most affected by syphilis in men who have sex with men. Goal: By reviewing the efforts under way in these 8 cities, we will understand the barriers and facilitators associated with Internet-based prevention efforts. Study: This is a review of Internet activities taking place in 8 major US cities. Results: Efforts in the 8 cities vary, with some cities reporting little or no Internet-based prevention activities. Other cities have attempted banner advertising, online outreach, online partner notification, online laboratory slips for syphilis testing, and auditorium-style chat sessions. Conclusion: Though a number of policy-related barriers prevent some cities from engaging in Internet-based prevention, these activities are clearly important to the overall prevention effort. In order to surmount local policy barriers, it is essential to obtain evaluation data from the programs initiated.