It has been argued that psychiatric nurses are ideally placed to provide smoking cessation interventions to patients with mental illness. This assumes that psychiatric nurses actively support smoking cessation. The current paper articulates some of the reasons why this has not occurred, in particular, some of the ethical beliefs held by nurses that may prevent such activity. Such an assumption also discounts the evidence that confirms psychiatric nurses to have among the highest smoking rates in nursing and in the health professions in general. The role and impact of the institution are also considered. In-depth interviews with seven community and inpatient psychiatric nurses were thematically analysed. Extensive individual and group discussions were also held with inpatient nurses from open and locked psychiatric settings during participant observation of the settings. The findings suggest that psychiatric nurses can be more effective in the primary care role of supporting patients' smoking cessation if they receive adequate institutional support to do so.