Background: Although previous studies had reported an important role of interleukin 13 (IL13) and its genetic polymorphisms in atopic dermatitis (AD), many of these previous reports focused on the missense variant rs20541 (Gln144Arg) without fine mapping of the gene region. Objective: To analyze the potential associations of other IL13 variants and their haplotypes with AD and assess total serum immunoglobulin E (IgE) levels. Methods: We performed fine mapping of single-nucleotide polymorphisms (SNPs) within the IL13 gene in a pilot study of 495 children with AD and 444 healthy controls. Then, we conducted a replication study of 757 children with AD and 1620 healthy controls to evaluate the association between the rs20541 variant of IL13 and AD. Results: In the pilot study, the rs20541 and rs1295685 SNPs in the 3ʹ-untranslated region of IL13 had significant associations with AD (P < .001 and. 01, respectively). In addition, 2 haplotypes (BL2_ht1 and BL2_ht2), which harbored the significant rs20541 and rs1295685 SNPs, had an association with AD (minimum P = .006). BL2_ht1 and BL2_ht2 had nominal signals associated with the total serum IgE levels (P < .05) but not with the severity of AD (P > .05). In the replication study, rs20541 was associated with the total serum IgE levels but not with the severity of AD. Conclusion: An additional IL13 gene SNP, rs1295685, has a strong linkage disequilibrium with rs20541, and its haplotypes are associated with AD and the total serum IgE levels.