TNF-related apoptosis inducing ligand (TRAIL) has been reported to induce apoptosis of autoreactive T cells and other inflammatory cells, and thus, it is a strong candidate gene for involvement in the development of autoimmune diseases. We investigated single nucleotide polymorphisms (SNPs) in the coding region of the gene at position 1595 in exon 5 in 128 Japanese patients with conventional/classical multiple sclerosis (MS) and 158 healthy controls. Patients with optico-spinal MS (OSMS) or atypical clinical attacks were excluded from the study. The frequency of CC genotype at position 1595 was significantly different between patients and controls (p=0.0027), and the C allele was more prevalent in the patients than in the controls (p=0.0138, OR=1.546, 95% CI=1.092-2.188). Logistic analysis, adjusted for HLA-DRB1*1501-positivity, revealed the independent association of the CC genotype with susceptibility to MS (p=0.0006, OR=2.393, 95% CI=1.453-3.943). There were no significant associations between +1595 polymorphism and the clinical features of MS. The results indicate that the presence of the CC genotype at position 1595 in exon 5 represents a higher risk of MS.