Objective The aim of this study was to investigate practice behaviours of Swedish physicians with regard to discussing the impact of cancer treatment on fertility with paediatric oncology patients and their parents, and to identify factors associated with such discussions. Methods A cross‐sectional survey study was conducted targeting all physicians in Sweden working in paediatric oncology care settings. Participants responded to a questionnaire measuring practice behaviour, attitudes, barriers, and confidence in knowledge. Multivariable logistic regression was used to determine factors associated with seldom discussing fertility. Results More than half of the physicians routinely talked with their patients/parents about the treatment's potential impact on fertility (male patients: 62%; female patients: 57%; P = 0.570). Factors associated with less frequently discussing fertility with patients/parents were working at a non‐university hospital (male patients: OR 11.49, CI 1.98–66.67; female patients: OR 33.18, CI 4.06–271.07), concerns that the topic would cause worry (male patients: OR 8.23, CI 1.48–45.89; female patients: OR 12.38, CI 1.90–80.70), and perceiving the parents as anxious (male patients: OR 7.18, CI 1.20–42.85; female patients: OR 11.65, CI 1.32–103.17). Conclusions Based on our findings, we recommend structured training in how to communicate about fertility issues in stressful situations, which in turn might increase fertility‐related discussions in paediatric oncology.