Background : All though the cause of alopecia areata is not known, many studies have recenty focused on the autoimmunity of alopecia areata. Objectives : The objectives of this study were to detect autoantibodies against hair follicular antigens and compare the autoantibody level before and after treatment of alopecia areata. Methods : We collected serum from : (a) 7 alopecia areata patients with good therapeutic responses, (b) 5 alopecia areata patients with poor therapeutic responses (c) 5 normal control people. First, we detected the antigens of hair follicles with SDS-PAGE. Secondly we reacted the antigens with the patients' and normal control serums by Western blotting. Results : The follicular antigens were seen in the range of 44kD-57kD. Autoantibodies obviously apparent in patients of alopecia areata but not in the normal control. High concentrations of were Autoantibodies against follicular antigens seemed to be present in the patients with good therapeutic responses and as they had been treated well, the level of autoantiboies has decreased. Autoantibodies, however, were present in small amounts and were almost an changed between before and after treatment in the patients with poor therapeutic responses except for one case. Conclusion : There are kinds of autoantibodies against hair follicles in the serums of alopecia areata patients, and the titers of antibodies may be correlated with therapeutic responses. (Korean J Dermatol 1998;36(6) : 1018~1023)