OBJECTIVE: To assess the impact of a partial smoking ban followed by a total smoking ban in a psychiatric hospital in Switzerland. METHODS: In 2003, smoking was allowed everywhere in psychiatric units. In 2004, smoking was prohibited everywhere except in smoking rooms. In 2006, smoking rooms were removed and smoking was totally prohibited indoors. Patients and staff were surveyed in 2003 (n=106), 2004 (n=108), 2005 (n=119) and 2006 (n=134). RESULTS: Exposure to environmental tobacco smoke (ETS) decreased after the partial ban and further decreased after the total ban. Among patients, after the total ban, more smokers attempted to quit smoking (18%) relative to before the total ban (2%, odds ratio=10.1, p=0.01). More smokers said that hospital staff gave them nicotine replacement products after the total ban (52%), compared with before (13%, odds ratio=7.6, p<0.001). Many participants (55%) commented that the total ban was too strict, and most (64%) preferred the partial ban. CONCLUSIONS: The partial ban decreased exposure to ETS and the total ban further improved the situation and increased the proportion of smokers who attempted to quit smoking and received nicotine medications. The total ban was loosely enforced and was overall acceptable, but most participants preferred a partial ban.