One of the speculated causes for sudden infant death syndrome (SIDS) is hereditary disease, in which long QT in electrocardiogram has been investigated in the view of mutations in various ion channel genes. In the present study, a novel QT interval determinant of SNP (rs10494366) in NOS1AP is genotyped in SIDS subjects (n=42) and the control group (n=210). Subjects carrying TT genotype was significantly associated with SIDS, compared with those carrying the TG of GG genotype (95% confidence interval 1.28-8.45). Sequence analysis revealed that one non-synonymous substitution in exon 8 (rs12817159) was observed in one subject, in addition to six common SNPs in exons and introns. This postmortem association study showed variations in NOS1AP might be involved in occurrence of SIDS.