Objective: In Denmark, more students smoke in vocational schools than in upper secondary schools. Smoking-prevention initiatives may reduce the prevalence of smoking but may also introduce unforeseen challenges. This study examined the significance of smoking and dilemmas related to smokefree school hours (SFSH) among established smokers in Danish vocational schools. Design: Qualitative research design. Setting: Data collection took place in a vocational education and training (VET) school in Denmark. The subject area was care, health and pedagogy (CHP). Method: Participant observation and focus groups were conducted with students and teachers. Two classes were observed for 2 weeks in total. The data analysed consisted of participant observation field notes (n = 10 school days), transcripts from student focus groups (n = 6; aged 18--56) and transcripts from teacher focus groups (n = 11). Results: Two dilemmas were described as faced by established smokers in relation to the implementation of smokefree school hours: (1) The school is entitled to make rules versus the right to decide for oneself; and (2) life and schoolwork are challenging and demanding versus school work is more important than smoking. Conclusion: The findings illustrate how smoking, as an ingrained everyday practice for established smokers, represents a means of coping with difficult school demands and everyday challenges, particularly for vulnerable students, and how regulations such as SFSH create dilemmas for those students. These dilemmas are important to consider when designing and implementing smoking-prevention initiatives to prevent potential negative side effects and an unintended increase in social inequality in smoking.