['Activation of coagulation and inflammation are parts of the innate host response to infection that may contribute to organ dysfunction and death when control of these systems is compromised. Thus, functional single nucleotide polymorphisms within candidate genes of the inflammation and coagulation cascade are possible factors which may influence severity and/or mortality in acute respiratory distress syndrome. The aim of this study was to investigate whether the factor V Leiden mutation (Arg506Gln) is associated with altered severity and/or mortality in acute respiratory distress syndrome.', 'Retrospective cohort, genetic association study.', 'Tertiary care intensive care unit.', 'Adults (white Germans) with acute respiratory distress syndrome (n = 106).', 'Genotyping for the factor V Leiden mutation.', 'Using Kaplan-Meier estimates to compare outcome, 30-day survival was significantly associated with the factor V Leiden mutation (p = .049). Thirty-day survival rates were 100% for Arg/Gln (n = 7) genotypes but only 58% for Arg/Arg (n = 99) genotypes, respectively.'] Is factor V Leiden mutation associated with improved 30-day survival in patients with acute respiratory distress syndrome?