Evidence has shown that interleukin-18 (IL-18) has both antitumor and pro-tumor effects in various types of leukemia. The current study aimed at investigating the contribution of IL-18 polymorphisms to the risk of childhood acute lymphocytic leukemia (ALL) in Taiwan. IL-18 promoter -656 (rs1946519), -607 (rs1946518), and -137 (rs187238) genotypes of 266 childhood ALL cases and 266 controls were determined by polymerase chain reaction-restriction fragment length polymorphism methodology. The distributions of genotypic and allelic frequencies of IL-18 rs1946519, rs1946518 or rs187238, were not significantly different between childhood ALL cases and controls (all p>0.05). However, in the stratification analysis among the cases, IL-18 rs187238 GC and CC genotypes were associated with increased childhood ALL risk and shorter survival (OR=4.19 and 2.93, 95%CI=2.04-8.64 and 1.19-7.23, p=0.0001 and 0.0250, respectively). No association was found with rs1946519 and rs1946518 (all p>0.05). IL-18 rs187238 GC and CC genotypes can serve as predictors for childhood ALL prognosis among Taiwanese. Validation in larger and various populations can greatly extend the feasibility of this novel predictor.