Alopecia areata (AA) is an autoimmune condition characterised by a T-cell mediated attack on the hair follicle. The inciting antigenic stimulus is unknown. A dense peribulbar lymphocytic infiltrate and reproducible immunologic abnormalities are hallmark features of the condition. The cellular infiltrate primarily consists of activated T-lymphocytes and antigen-presenting Langerhans cells. T-lymphocytes play a critical role in the pathogenesis of disease. The observance of hair regrowth in those with alopecia areata who are treated with cyclosporine, a known inhibitor of T-cell function, further confirms the central role of the T-lymphocytes in the development of the disease.