Febrile seizures are the most common form of childhood seizures. Although the literature associates certain micronutrients with febrile seizures, there is limited information about the effects of such micronutrients. This study aimed to determine the relationship between serum selenium level and simple febrile seizures in children. This case-control study was conducted in the Children's Hospital in Qazvin, Iran, in 2008. The serum selenium level of 30 children who experienced simple febrile seizures (case group) was measured and compared with that of 30 febrile children without seizure (control group). The serum selenium level was measured by flame atomic absorption spectrophotometer. Data were analyzed by using t-test. Mean ± standard deviation of serum selenium level in the case and control groups was 44.4 ± 10.9 and 63 ± 9.78 μg/dL, a significant difference (P < 0.001). In the case group, 18/30 patients (60%) had a serum selenium level below the norm of 46 μg/dL, whereas serum selenium level in the entire control group was within the normal range (P < 0.01). The serum selenium level in the children who had simple febrile seizures was significantly lower than in the nonseizure control group. It seems that there is an association between serum selenium deficiency and simple febrile seizures; however, further study is recommended.