<span class="Bold">Background</span> The prevalence of smoking among patients with psychiatric disorders is 3-4 times higher than the general population. However, smoking is still permitted in many psychiatric clinics. The National Prevention Agreement (2018) mandates that all psychiatric wards be smoke-free by 2025. The UMC Utrecht clinics have been smoke-free since November 2020. <span class="Bold">Aim</span> To examine healthcare workers’ attitudes before and after implementing the smoke-free policy. <span class="Bold">Method</span> In an observational study with quantitative data analysis, data were collected in one center from healthcare workers in psychiatry departments with surveys. We collected demographic information, smoking status, attitudes towards the smoke-free policy, and its impact on patients and care. Incidents of aggression were prospectively recorded and reported in the MAP (aggression incidents in patient care). <span class="Bold">Results</span> Out of 172 healthcare workers invited to participate, 30% (n = 52) completed the pre-implementation survey, and 20% (n = 34) completed the post-implementation survey. Prior to implementation, 62% (n = 32/52) of healthcare workers had a positive attitude towards the smoke-free policy, which increased to 77% (n = 26/34) post-implementation. Expectations of increased aggression incidents were reported by 62% (n = 32/52) during the pre-implementation phase. The number of aggression incidents was 46 in the one-year period before implementation (November 2019 – February 2020) and 45 incidents after implementation (November 2020 – February 2021). <span class="Bold">Conclusion</span> This study supports the implementation of a smoke-free policy in psychiatric clinics due to the lack of a significant increase in aggression incidents. Healthcare workers perceived this outcome and observed quicker granting of ‘green’ freedoms.