Background: Acute lower respiratory infection (ALRI) is the leading cause of child mortality, especially in the developing world. Polymorphisms in the interleukin 4 (IL-4) gene have been linked to a variety of human diseases. Objectives: To investigate whether the IL-4 -590C/T (rs2243250) polymorphism could be a genetic marker for susceptibility to ALRIs in young Egyptian children. Methods: This was a multicenter study conducted on 480 children diagnosed with pneumonia or bronchiolitis, and 480 well-matched healthy control children. Using PCR-RFLP analysis, we genotyped a -590C/T (rs2243250) single nucleotide polymorphism of the IL-4 gene promoter, meanwhile the serum IL-4concentration was measured by ELISA. Results: The frequency of the IL-4 -590 T/T genotype and T allele were overrepresented in patients with ALRIs in comparison to the control group (OR = 2.0; [95% confidence interval [CI]: 1.38-2.96]; for the T/T genotype) and (OR: 1.3; [95%CI: 1.07-1.56]; for the T allele; P < 0.01). The IL-4 -590 T/T genotype was associated with significantly higher mean serum IL-4 concentration (58.7 ± 13.4 pg/mL) compared to the C/T genotype (47.6 ± 11 pg/mL) and the C/C genotype (34.8 ± 9.6 pg/mL); P < 0.01. Conclusion: The IL-4 -590C/T (rs2243250) polymorphism may contribute to susceptibility to ALRIs in young Egyptian children. Keywords: acute lower respiratory infections; children; gene polymorphism; interleukin 4.