Introduction: The androgen receptor (AR) gene possesses polymorphic CAG-repeats coding poly glutamine residues near the androgen-binding site of AR molecule. It has been shown that the length of CAG-repeats was related to the development of the andorogenetic alopecia (AGA)．
Objective: The purpose of this study was to test the association between the CAG-repeats and clinical effects of finasteride to know whether the CAG repeats can be utilized as a measure to select a potential patient for finasteride treatment.