In the overall analysis, we did not find significant association between IL-18 −137G/C polymorphism and the risk of allergic disease under all models (C allele versus G allele: OR = 0.93, 95% CI = 0.80–1.07, P = 0.31; CC + CG versus GG: OR = 0.97, 95% CI = 0.82–1.14, P = 0.70; CC versus CG + GG: OR = 0.77, 95% CI = 0.58–1.02, P = 0.07; CC versus GG: OR = 0.76, 95% CI = 0.55–1.04, P = 0.08; CG versus GG: OR = 1.02, 95% CI = 0.88–1.18, P = 0.78, Figure 3). This evidence concerns the gene IL18 and allergic disease.