Alopecia areata (AA) affects both sexes with a cumulative lifetime incidence of about 2% and no significant racial predominance. The condition is known to carry a considerable impact on health‐related quality of life. to evaluate serum level of 8-Hydroxydeoxyguanosine (8-OHdG) in patients with alopecia areata and to assess its clinical significance. study that included 50 patients suffering from AA. In addition, 30 apparently healthy individuals of matched age and sex as a control group. All patients were selected from the outpatient clinic of Dermatology, Andrology, and Venereology Department of Benha University Hospitals. All patients were subjected history taking. Clinical examination and serum level of 8-OHG. The mean age of AA was 30.7±11.4 years old and the majority of the patients were males. the serum level of 8-OHdG was significantly higher among AA patients than in control group and the difference was statistically significant (P-value =0.018). In addition, 8-OHDG showed fair diagnostic accuracy for the detection of AA. At cut off value of 18.1ng/ml, it has a sensitivity of 70% and a specificity of 60% for diagnosis of AA. we found that the serum level of 8-hydroxy-2′-deoxyguanosine (8-OHdG) was significantly higher in AA patients than healthy controls. In addition, serum 8-OHdG is a promising diagnostic and prognostic biomarker for AA. We found that serum 8-OHdG had fair diagnostic accuracy for the detection of AA presence and severity.