Despite tremendous public and media interest in murder-suicide, scientific research that sheds new light on either the prevalence of mental disorders among perpetrators of mass murder-suicide or the role of mental disorders when they appear relevant has been rare. I outline several assumptions and challenges that may encumber scholarship in this area but also identify some promising avenues for future research. Greater scientific understanding of any associations between mental disorders and murder-suicide could lead to more evidence-based interventions that could help prevent these lethal attacks.In recent decades, incidents of mass murder-suicide-including mass shootings and suicide terrorism-have received a great deal of attention from the public, the media and scholars. However, research that sheds new light on either the prevalence of mental disorders among these perpetrators or the role of mental disorders in their violent behaviour has been rare. This is partly evidenced in the review by Theodorou and colleagues (2024) in this issue of CBMH, which found only 60 qualifying studies on family, mass shooter and terrorist perpetrators combined. Below, I outline several assumptions and challenges that may encumber scholarship in this area and then identify some promising avenues for future research.