The case-control study examined the association between specific polymorphisms in several genes coding for specific inflammatory responses and for surfactant protein and their potential association with increased susceptibility to ARDS. The first objective was to assess the role of candidate-gene polymorphisms as risk factors for ARDS in a case-control study. The second objective was to assess the relationship between genotype and phenotype for candidate markers in cases and controls. The third objective was to assess the role of these polymorphisms in clinical outcome (survival, recovery) using patients from both the proposed case-control study and the multicenter case series and clinical trial sponsored by the NHLBI ARDS network. By combining both a large case-control study and case series from the network, the study had the advantages of sufficient case ascertainment, statistical power, diagnostic standardization, uniform outcome criteria and study efficiency. Overall, the results of this study should provide new insights into the epidemiology of ARDS and allow for possible preventive strategies as well as possible modifications of therapeutic interventions for the Network Phase III trials.