Four months after Group Health Cooperative of Puget Sound adopted a policy prohibiting smoking in its 35 facilities, we assessed attitudes and behavior of a sample of 447 employees. Results indicated that 85 per cent of employees approved of the decision to go smoke-free, the rate of reported smoking decreased, and a large proportion of non-smokers believed that their own and co-workers' work performance had improved. Suggestions for successful implementation of future programs are provided.