Alopecia areata (AA) is a common non-scarring, inflammatory type of hair loss that affects people of all ages and genders. It has been shown that 1,25-dihydroxyvitamin D(3) receptors (VDRs) are highly expressed in the keratinocytes of human and murine hair follicles and the absence of expression of VDRs is associated with reduced hair follicle growth and epidermal differentiation. Reduced VDR expression in the hair follicles of affected areas has also been observed in studies of AA patients’ scalps.