Death in low-risk patients is not studied as frequently as it is in other cardiac patients. We, therefore, sought to determine why some low-risk patients die after cardiac surgery. All low-risk patients (EuroSCORE<or=2) who died after cardiac surgery in one institution between 1996 and 2005 were included and meticulously studied by internal and independent external review of preoperative, operative and postoperative information from the case-notes and post-mortem findings. Deaths were classified into non-cardiac and cardiac and further subclassified into unavoidable deaths or due to failure in achieving a satisfactory cardiac outcome (FIASCO). Between 1996 and 2005, there were 16 deaths in 4294 low-risk patients (mortality 0.37%). Internal and external review agreed that nine deaths were non-preventable (CVA, bronchopneumonia, etc.) and that avoidable FIASCO accounted for seven deaths. Of the deaths considered to be preventable, all had probable errors of technique and three also had additional system errors. No cardiac operation is without risk. Mortality, though fortunately rare, can still occur, even in low-risk patients. Despite an extremely low mortality in the low-risk group FIASCO still accounts for nearly one-half of deaths. This suggests that mortality may be reduced even further as part of a quality improvement programme.