Abstract： Recent studies have implied that mast cells are involved in the pathogenesis of skin diseases,especially inflammatory skin diseases.Alopecia areata (AA) is a form of non-scarring inflammatory hair loss of unknown etiology.At present,AA is thought to be a T-cell mediated autoimmune reaction specifically targeting anagen hair follicles.It has been demonstrated that increased mast cells in AA lesions are associated with the expression of neuropeptides,and various inflammatory mediators released by activated mast cells via degranulation may participate in the inflammatory infiltration in AA.The fact that prophylactic use of antihistamines and mast cell stabilizers is effective for the treatment of patients with AA who poorly respond to traditional therapy or have inherited predisposition to allergy hints that mast cells may be involved in the pathogenesis of AA.