Gray GW, Sargsyan AE, Davis JR. Clinical risk management approach for long-duration space missions. Aviat Space Environ Med 2010; 81:1128–32. Introduction: In the process of crewmember evaluation and certification for long-duration orbital missions, the International Space Station (ISS) Multilateral Space Medicine Board (MSMB) encounters a surprisingly wide spectrum of clinical problems. Some of these conditions are identified within the ISS Medical Standards as requiring special consideration, or as falling outside the consensus Medical Standards promulgated for the ISS program. Methods: To assess the suitability for long-duration missions on ISS for individuals with medical problems that fall outside of standards or are otherwise of significant concern, the MSMB has developed a risk matrix approach to assess the risks to the individual, the mission, and the program. The goal of this risk assessment is to provide a more objective, evidence- and risk-based approach for aeromedical disposition. Using a 4 × 4 risk matrix, the probability of an event is plotted against the potential impact. Event probability is derived from a detailed review of clinical and aerospace literature, and based on the best available evidence. The event impact (consequences) is assessed and assigned within the matrix. Results: The result has been a refinement of MSMB case assessment based on evidence-based data incorporated into a risk stratification process. This has encouraged an objective assessment of risk and, in some cases, has resulted in recertification of crewmembers with medical conditions which hitherto would likely have been disqualifying. Conclusions: This paper describes a risk matrix approach developed for MSMB disposition decisions. Such an approach promotes objective, evidence-based decision-making and is broadly applicable within the aerospace medicine community.