Keshan disease (KSD), a potentially fatal cardiomyopathy, has very high incidence in some selenium-poor regions of China. KSD may be accompanied with a variety of arrhythmia, which is associated with mutations in the gene coding for cardiac voltage-gated sodium channel (SCN5A). The molecular mechanism of KSD is still largely obscure. We aimed to determine the association between the H558R polymorphism of SCN5A and KSD. We recruited 71 patients with KSD and 80 geographical region-matched control subjects in our study.