Suicidal behavior (SB) as a serious public health problem is partly heritable.Identifying the genes and the neurobiologic pathways relevant to suicidal behavior is important for preventative strategies.One family-based study using data on 77 trios of suicide attempters reported an association between sodium channd voltage gated type Ⅷ alpha (SCN8A) and SB and found overtransmission of an introuic polymorphism.In order to investigate the role of SCN8A in Chinese SB subjects, we analyzed five SNPs within the region of the SCNgA gene in each group of 329 nonsuicide attempts and 297 suicide attempts.In the five SNPs, there were no significant differences in genotype or allele frequencies between these two groups nor in haplotype distributions.Our findings suggest that it is unlikely that the SCN8A gene is involved in susceptibility to suicidal behavior in the Han Chinese population.