Background. Recent studies suggest that mutation of the slow delayed rectifier potassium channel (IKs) contributes to familial atrial fibrillation (FAF). In the current study, we identified common genetic variants ofKCNQ1and explored the potential association betweenKCNQ1polymorphism with lone AF (LAF).Methods. Clinical data and blood samples were collected from 190 Han Chinese patients with sporadic AF and matched healthy controls. Variants of theKCNQ1gene were identified using single-strand conformational polymorphism (SSCP) analysis. A case-control association study inKCNQ1identified six known single-nucleotide polymorphisms (SNPs) during SSCP screening of the 190 LAF patients and 190 healthy controls.Results. One of the SNPs inKCNQ1was strongly associated with LAF; significant allelic association was detected rs59233444 (P=0.013,OR=1.469, 95% confidence interval (CI): 1.083–1.993). A multiple regression analysis indicated that rs59233444 is an independent risk factor for LAF. Twelve new variants were identified inKCNQ1, including one in the 5′-UTR, two in the 3′-UTR, six in introns, two synonymous substitutions, and one missense substitution. Variants c.1009C>T, c.1860C>T, and c.+2285C>T were not present in the 190 controls, and the others were identified in controls at various frequencies.Conclusions. rs59233444, a common SNP but not mutation in the coding regions of theKCNQ1gene, is a risk factor for LAF in Chinese Han population.