Asthma is a chronic inflammatory disease of respira tory ducts caused by genetic and environmental fact ors. Free radicals play a role in pathogenesis of asthma on o ne hand and antioxidants, which are comprised of ra rely found ingredients such as selenium and zinc, act as defen se factors against negative effects of radicals on the other hand. Knowing that asthma increases oxidative stress it i s assumed that selenium plays a key role in asthma pathogenesis. Relationship between prevalence/severity of asthma and selenium level has been proven by empirical fin dings of studies on some of the human studies. All the asthm atic children who referred to pediatric clinic of K horramabad Shahid Madani Hospital, Iran constituted the study population of the present analytical cross-sectiona l study. 65 asthmatic and 65 healthy children were selected as experiment and control groups. Variables such as: a ge, gender, domicile, exposure to cigarette smock, number of fa mily members, history of asthma and allergy in the family, and type of feeding during infancy were surveyed by a q uestionnaire. In addition, blood samples were colle cted to measure selenium level. The experiment group was co mprised of 40 boys and 25 girls and these figures i n the control group were 36 and 29 respectively. 8% of gi rls and 5% of boys in the asthma group had selenium deficiency However; Fisher’s test showed that the difference w as not significant. Among the asthmatic children fr om rural areas, 12.9% had selenium deficiency and no such de ficiency was observed among children from urban are as. Therefore, there was significant relationship betwe en selenium deficiency and domicile of asthmatic ch ildren (p = 0.031). In addition, no significant difference was observed regarding serum level of selenium of asthm atic children based on number of family members, asthma, family h istory of asthma and allergy, type of infancy nutri tion, and exposure to cigarette. Deficiency of selenium was o bserved in 2.6% and 1.3% of asthmatic and healthy c hildren respectively, which indicated no significant differ ence. There was no significant difference between a sthmatic and healthy children in Khoramabad city regarding serum level of selenium. Therefore, there is no need for selenium supplements for asthmatic children.