Asthma is a multifactorial respiratory disease determined by interactions of multiple disease susceptibility genes and environmental factors. IL-18 is an important cytokine for initiating and perpetuating the catabolic and inflammatory response in allegic asthma. A number of SNPs that influence IL-18 production are found in the gene promoter region.The aim of this study was to investigate the association of IL-18 -607 C/A promoter polymorphism with asthma and whether this polymorphism influenced the severity of asthma in affected children. The influence of this promoter gene polymorphism on total serum IgE level in studied subjects was investigated.This study included 40 asthmatic children, subdivided into four groups according to different degrees of asthma severity, and 20 healthy subjects were included as control group.