The explosive growth in access to the Internet suggests that the Internet may be a viable channel through which we can reach and treat the large population of smokers who are unlikely to use other modes of intervention. We applied national guidelines from the U.S. Public Health Service to assess the quality of interventions for smoking cessation that are available on the Internet. The Public Health Service guidelines were codified into two instruments to record and to rate quality of the intervention contents. Usability guidelines established by the National Cancer Institute were used to develop an instrument to assess Web site usability. Of the 202 Web sites identified in searches, 77% did not provide direct intervention over the Internet and were excluded from analyses. A total of 46 Web sites were included in our review. Usability assessments showed mixed results. Web sites were visually well organized and used consistent graphical design; however, reading difficulty averaged above the 8th-grade level. Over 80% of Web sites provided no coverage of one or more of the key components of tobacco treatment recommended in the guidelines. Ironically, areas receiving the least coverage were those most amenable to the interactive capabilities of the Internet, such as providing tailored, personalized advice to quit and arranging follow-up contact. Smokers seeking quality tobacco dependence treatment on the Internet may have difficulty distinguishing among the numerous Web sites available. Web sites that provide direct treatment often fail to fully implement treatment guidelines and do not take full advantage of the interactive and tailoring capabilities of the Internet.