In recent years, there has been increased interest in the development of prophylactic and diagnostic tools for patients at high risk for invasive aspergillosis (IA), resulting in a significant investment of human, technical, and economic resources. There are several classic risk factors for the development of IA, including neutropenia, graft-versus-host disease, and corticosteroid use. However, despite having similar risk profiles, only a subset of at-risk individuals will develop this fungal complication. At present, there is a significant expansion of the classically defined 'high-risk' group due to the ageing of the general population, the intensification of treatment strategies, and the introduction of new drugs into clinical practice (e.g., monoclonal antibodies, TNF inhibitors). Therefore, an improved categorization of patients would be useful in order to better target available resources and avoid the risk of potential overtreatment and toxicities.