No / Alopecia areata is an immunologically mediated disease characterized by extreme variability not only in the time of initial onset of hair loss but in the duration, extent and pattern of hair loss during any given episode of active loss. These variables, as well as the unpredictable nature of spontaneous regrowth and lack of a uniform response to various therapies, has made clinical trials in alopecia areata difficult to plan and implement. In fact, there are currently no drugs FDA-approved specifically for the indication of alopecia areata. To help facilitate well-controlled clinical trials for alopecia areata, this National Alopecia Areata Foundation (NAAF) sponsored subgroup of investigators/clinicians experienced in clinical trials and/or in the clinical care of patients with alopecia areata has outlined some general principles and potential endpoints for clinical studies in alopecia areata. These guidelines build on the Alopecia Areata Investigational Assessment Guidelines published in 1991 which established baseline clinical staging and background information important to gather on any alopecia areata patient involved in clinical research.