Casein kinase I gamma 2 isoform (CSNK1G2), a member of the large casein kinase I (CKI) family, may affect the development of brain, and associate with vesicular trafficking and neurotransmitter releasing from small synaptic vesicles. Based on our previous linkage analysis data that mapped our simple febrile seizures (FS) families to 19p13.3 and the function of CSNK1G2 in this region, CSNK1G2 was chosen as a candidate gene for FS. All of the 13 exons and their flanking introns of the CSNK1G2 gene were amplified and sequenced, and 10 single nucleotide polymorphisms (SNPs) were found. Using the three SNPs we found as markers, we conducted association studies in 60 FS patients and 101 normal controls. Allele and genotype frequencies of the SNPs IVS2-33C > T and 837C > T as well as the haplotype of the two SNPs were significantly different between FS patients and controls (P < 0.05). This study suggests that CSNK1G2 gene may be a susceptibility gene for FS in the northern Chinese Han population.