Aims Although smoking prevalence among people with severe mental illness is high, it remains largely unaddressed. This pragmatic pilot project aimed to develop and implement a tailored tobacco dependence service in mental health settings and to assess its impact, as well as barriers and facilitators to implementation. Design An integrative service model, spanning acute, rehabilitation and community services, including the design of tailored instruments and referral pathways, delivered by two mental health professionals. Setting and participants Four adult acute and two rehabilitation wards (129 beds), and the community recovery team (2038 cases) of the United Kingdom's largest Mental Health Trust. Measurements Audit of smoking information in patient notes; service uptake; quit attempts; smoking cessation and reduction; qualitative data on implementation barriers/facilitators. Findings A total of 110 patients attended at least one support session: 53 inpatients (23% of inpatient smokers) and 57 community (of unknown number of community smokers, as recording of smoking status is not mandatory). Thirty-four of these (31%) made a quit attempt; 17 (15%) stopped smoking and 29 (26%) reduced cigarette consumption by up to 50% at the final contact. Barriers to service implementation related to: (i) trust policy, systems and procedures, (ii) staff knowledge and attitudes and (iii) illness-related factors. Conclusions Despite the strong anti-smoking climate in the United Kingdom, including a law requiring smoke-free policies in mental health settings, establishing a smoking cessation treatment service for people with mental illness proved difficult, due to complex systemic barriers. However, there is clearly a demand, by patients, for such a service.