Introduction Children are important stakeholders in discussions about regulation of smoking and protection from secondhand smoke, but are rarely acknowledged as such. We explored the opinion of pediatric patients and other key stakeholders regarding the planned smoke-free zone around the Erasmus MC, a large university hospital in the Netherlands. Methods In 2019, we conducted a survey among pediatric patients and their parents, Erasmus MC employees, visitors, and adult patients, before implementation of the outdoor smoke-free zone, to assess their opinions on smoking and the planned smoke-free policy. Qualitative and quantitative data were collected and analyzed mostly using descriptive statistics and thematic analysis. Results In all, 91 parent-child dyads and 563 employees, visitors, patients and students filled in the questionnaires. Over 90% of children reported that they were regularly exposed to tobacco smoke, most often on the streets. Many underlined the exemplary role of healthcare providers, and 89% felt that nobody should be allowed to smoke near the hospital. Among parents, 89% were (very) positive towards the planned implementation of the smoke-free zone. In addition, 70% of adult patients, 81% of employees, 65% of visitors, 89% of students and 75% of ‘others’ were (very) positive about the new smoke-free policy. Smokers and former smokers generally were less positive about the policy. Conclusions Children generally disapproved smoking around a hospital and felt that healthcare providers should be a good example concerning not smoking. The majority of adult patients, employees and visitors support a smoke-free zone surrounding the hospital, and virtually all pediatric patients and their parents do. Children should be acknowledged as important stakeholders in smoke-free policies and should be involved in planning and implementation.