Abstract Background Relatives have no formal position in the practice of euthanasia and physician-assisted suicide (EAS) according to Dutch legislation. However, research shows that physicians often involve relatives in EAS decision-making. It remains unclear why physicians do (not) want to involve relatives. Therefore, we examined how many physicians in the Netherlands involve relatives in EAS decision-making and explored reasons for (not) involving relatives and what involvement entails. Methods In a mixed-methods study, 746 physicians (33% response rate) completed a questionnaire, and 20 were interviewed. The questionnaire included two statements on relatives’ involvement in EAS decision-making. Descriptive statistics were used, and multivariable logistic regression analyses to explore characteristics associated with involving relatives. In subsequent interviews, we explored physicians’ views on involving relatives in EAS decision-making. Interviews were thematically analysed. Results The majority of ...