<sec id="liv12157-sec-0001"> Background & AimsSingle nucleotide polymorphisms (SNP) in the Cytotoxic T lymphocyte antigen-4 gene (CTLA-4) have been associated with several autoimmune diseases including autoimmune Hepatitis (AIH). In this chronic idiopathic inflammatory liver disease, conflicting results have been reported on the association with a SNP at position +49 in the CTLA-4 gene in small patient cohorts. Here, we established the role of this SNP in a sufficiently large cohort of AIH patients. <sec id="liv12157-sec-0002"> MethodsThe study population consisted of 672 AIH patients derived from academic and regional hospitals in the Netherlands and was compared with 500 controls selected from the Genome of the Netherlands' project cohort. Genotype frequencies were assessed by PCR for patients and by whole genome sequencing for controls. <sec id="liv12157-sec-0003"> ResultsNo significant differences in allele frequencies were found between patients and controls (G Allele: 40% vs 39%, P=0.7). Similarly, no significant differences in genotype frequencies between patients and controls were found. Finally, there was no relation between disease activity and the G allele or AG and GG genotypes. <sec id="liv12157-sec-0004"> ConclusionThe Cytotoxic T Lymphocyte Antigen-4 +49 A/G polymorphism does not represent a major susceptibility risk allele for AIH in Caucasians and is not associated with disease severity at presentation.