Objective A functional polymorphism at codon 55 of the small ubiquitin like modifier 4 (SUMO4) gene (methionine to valine,M55V) was recently found to be associated with type 1 diabetes mellitus mainly in Asian populations (T1D) In the present study, we aimed to investigate whether this locus also contributes to the genetic susceptiblity to type 1 diabetes in Chinese Research design and methods A case-control study was performed using genomic DNA samples from 165 unrelated Chinese childhood T1D subjects and 160 normal blood donors The SUMO4 M55V single nucleotide polymorphism (SNP) was genotyped using polymerase chain reaction (PCR) amplification followed by digestion with the restriction enzyme Mse I Results The frequencies of SUMO4 163G allele were significantly increased in T1D patients (38 2% vs healthy control subjects 28 7%, P<0 05, OR=1 51, 95% CI 1 03-2 13) SUMO4 163 GG genotype was also significantly increased in the T1D patients (17% vs healthy control subjects 8%, P<0 05) Conclusions This study indicates that the SUMO4 gene M55V variant is associated with the genetic susceptibility of T1D in Chinese children