The SCN5A gene encodes the alpha subunit of the human cardiac voltage-gated sodium channel. Mutations in SCN5A are responsible for Brugada syndrome, an inherited cardiac disease that leads to idiopathic ventricular fibrillation (IVF) and sudden death. In this study, we screened nine individuals from a single family and 12 sporadic patients who were clinically diagnosed with Brugada syndrome. Using PCR-SSCP, DHPLC, and DNA sequencing analysis, we identified a novel single missense mutation associated with Brugada syndrome in the family and detected a C5607T polymorphism in Korean subjects. A single nucleotide substitution of G to A at nucleotide position 3934 changed the coding sense of exon 21 of the SCN5A from glycine to serine (G1262S) in segment 2 of domain III (DIII-S2). Four individuals in the family carried the identical mutation in the SCN5A gene, but none of the 12 sporadic patients did. This mutation was not found in 150 unrelated normal individuals. This finding is the first report of a novel mutation in SCN5A associated with Brugada syndrome in Koreans.