To study the genetic polymorphism of 5-α reductase type II enzyme in relation to oxidative stress in cases of androgenetic alopecia (AGA) in a sample of Egyptian population. Materials and Methods: This study was conducted on 45 patients with different grades of AGA,and 45 healthy subjects as control group. Laboratory tests included DNA extraction from blood, amplification of the 5-α reductase type II by PCR and V89L mutation analysis by restriction endonuclease enzyme RsaІ, and estimation of the levels of plasma catalase and erythrocyte lysate superoxide dismutase (SOD) enzymes by colorimetric methods. Results: The studied subjects carrying the homozygote(LL) and the heterozygote (VL) genotypes were of no risk of developing AGA.(OR=0). Regarding the leucine allele, the studied subjects carrying the (L) allele were at about 3.7 higher risk of AGA .(OR=3.692), and the results were statistically significant (p<0.001). There was significant increase in the level of SOD and catalase in patients than in control group(p=0.005),and (p<0.001) respectively,plasma catalase is significantly higher in patients with LLvariant than inVL variant (p=0.020). Asignificant relations was found between the severity of the disease and age and family history (p=0.037), and (0.036) respectively, there was no significant correlation between the level of catalase enzyme and SOD in one hand and the severity of the disease among patients. Conclusions: There is a possible association between AGA and V89L genetic polymorphism of 5-alpha reductase type II enzyme, patients carrying the mutant leucine (L) allele have a risk for developing AGA. Also there is possible association between AGA with oxidative stress.