The implementation of a smoke-free policy in this medical center was associated with a decrease in the prevalence of regular cigarette smoking from 16.7 percent to 13.8 percent and a smoking cessation rate of 22.5 percent among regular smokers over the 2 1/2 years since the policy was announced. This decrease in prevalence is the result of both smoking cessation among existing employees and less frequent regular smoking among new employees. At two-year follow-up, the policy was overwhelmingly endorsed by medical center staff overall but was viewed less favorably by those who continued to smoke. Nevertheless, over the 2 1/2 years, many of these smokers have been in the action stage of cessation (37.1 percent made a serious attempt to stop smoking, 20.7 percent had used nicotine polacrilex in a smoking-cessation effort, and 13.8 percent had attended a formal cessation program). The implementation of a smoke-free policy has made a significant contribution toward providing a healthful work environment and toward encouraging nonsmoking behavior in staff and patients.