Alopecia areata (AA) is an immune-mediated form of hair loss that affects all ages and both sexes. Selenium (Se) is an essential micronutrient that has an immune-modulatory role and regulates oxidative stress (OST). The aim of this work was to detect serum selenium level in Egyptian patients with alopecia areata. The results revealed significant decrease in serum Se level in AA patients (60.2 ± 8.8 µg/L) in comparison to controls (77.4 ± 9.6 µg/L). This decrease was more in extensive AA than in the mild form.