In the present study, we assessed the potential association of missense polymorphisms of the SFTPA1, SFTPA2 and SFTPD genes as well as the resulting haplotypes, with the susceptibility to and the severity and outcome of CAP in adults. In addition, we evaluated the existence of linkage disequilibrium (LD) among these genes, and the effect of genetic variability on SP-D serum levels.